阅读说明：本技术 波导结构的制造 (Fabrication of waveguide structures ) 是由 弗兰克·佐格 乔舒亚·韦恩·帕克斯 于 2019-05-21 设计创作，主要内容包括：一种制造波导结构以从波导层形成固体芯波导的方法可以包括：向波导层中蚀刻流体通道；向波导层中蚀刻第一空气间隙和第二空气间隙,其中,蚀刻第一空气间隙和第二空气间隙创建了在波导层中的在第一空气间隙与第二空气间隙之间的固体芯波导。一种用于制造波导结构以形成固体芯波导的方法可以包括：在衬底层中形成第一沟槽、第二沟槽和第三沟槽；以及在机械加工的衬底层上沉积波导层,其中,沉积波导层在与第一沟槽对应的位置处创建流体通道的中空芯,并且在波导层中与第二沟槽与第三沟槽之间的区域对应的位置处创建固体芯波导部分。(A method of fabricating a waveguide structure to form a solid core waveguide from a waveguide layer may comprise: etching a fluid channel into the waveguide layer; etching a first air gap and a second air gap into the waveguide layer, wherein etching the first air gap and the second air gap creates a solid core waveguide in the waveguide layer between the first air gap and the second air gap. A method for fabricating a waveguide structure to form a solid core waveguide may comprise: forming a first trench, a second trench and a third trench in the substrate layer; and depositing a waveguide layer on the machined substrate layer, wherein the depositing the waveguide layer creates a hollow core of the fluid channel at a location corresponding to the first trench and creates a solid core waveguide portion in the waveguide layer at a location corresponding to a region between the second trench and the third trench.)

1. A method for fabricating a waveguide structure to form at least one solid core waveguide from a waveguide layer, the method comprising:

etching a fluid channel into the waveguide layer;

etching a first air gap and a second air gap into the waveguide layer;

wherein etching the first air gap and the second air gap creates a solid core waveguide in the waveguide layer between the first air gap and the second air gap; and

attaching a cover layer to the waveguide layer to close the fluidic channel.

2. The method of claim 1, wherein the waveguide layer comprises a first oxide layer and a second oxide layer, wherein the first oxide layer is located on a first side of the second oxide layer and has a first refractive index, and the second oxide layer has a second refractive index lower than the first refractive index.

3. The method of claim 2, wherein:

etching the fluid channel comprises: etching into the second oxide layer and the first oxide layer at a time;

etching the first air gap comprises: etching into the second oxide layer and the first oxide layer at a time; and

etching the second air gap comprises: etching into the second oxide layer and the first oxide layer at a time.

4. The method of any of claims 2 to 3, wherein:

the waveguide layer further comprises a third oxide layer located on a second side of the second oxide layer opposite the first side, wherein the third oxide layer has a third refractive index lower than the first refractive index, and

etching the fluid channel comprises: etching into the third oxide layer, the second oxide layer, and the first oxide layer at a time;

etching the first air gap comprises: etching into the third oxide layer, the second oxide layer, and the first oxide layer at a time; and is

Etching the second air gap comprises: etching into the third oxide layer, the second oxide layer, and the first oxide layer at a time.

5. The method of any of claims 1 to 4, further comprising: doping the waveguide layer to create one or more doped regions in the waveguide layer having a doping index lower than a surrounding index, wherein the one or more doped regions are adjacent to the solid core waveguide.

6. The method of claim 5, wherein the one or more doped regions are adjacent to the first and second air gaps.

7. The method of any one of claims 5 to 6, wherein the one or more doped regions are adjacent to the fluid channel.

8. The method of any of claims 1 to 7, further comprising: doping the waveguide layer to create one or more doped regions in the waveguide layer having a higher doping index than a surrounding index, wherein the one or more doped regions form the solid core waveguide.

9. The method of any one of claims 1 to 8, wherein:

the waveguide structure comprises an ARROW layer;

etching the fluid channel comprises: etching into the waveguide layer, but not into the ARROW layer;

etching the first air gap comprises: etching into the waveguide layer, but not into the ARROW layer; and is

Etching the second air gap comprises: etching into the waveguide layer and not into the ARROW layer.

10. The method of any one of claims 1 to 9, wherein:

the waveguide structure comprises an ARROW layer;

the waveguide structure comprises an etch stop layer between the ARROW layer and the waveguide layer at a location corresponding to the fluidic channel;

etching the fluid channel comprises:

etching into the waveguide layer, but not into the ARROW layer;

dissolving the etch stop layer;

etching the first air gap comprises: etching into the waveguide layer and the ARROW layer at a time; and is

Etching the second air gap comprises: etched into the waveguide layer and the ARROW layer at a time.

11. The method of any one of claims 1 to 10, wherein:

the waveguide structure comprises an ARROW layer;

etching the fluid channel comprises: performing dry etching, followed by wet etching;

etching the first air gap comprises: performing dry etching, followed by wet etching; and is

Etching the first air gap comprises: dry etching is performed, followed by wet etching.

12. The method of any one of claims 1 to 11, wherein:

the waveguide structure comprises an ARROW layer;

etching the fluid channel comprises: partially etching into the waveguide layer without etching through the waveguide layer to the ARROW layer;

etching the first air gap comprises: etching into the waveguide layer and the ARROW layer at a time; and is

Etching the second air gap comprises: etched into the waveguide layer and the ARROW layer at a time.

13. The method of claim 12, wherein:

etching the first air gap comprises: etching into the waveguide layer, the ARROW layer and the substrate layer at a time;

etching the second air gap comprises: etching into the waveguide layer, the ARROW layer, and the substrate layer at a time.

14. The method of any one of claims 1 to 13, wherein:

the waveguide structure includes an ARROW layer below the waveguide layer;

the waveguide structure includes an etch stop layer between the ARROW layer and the waveguide layer, the etch stop layer extending to a location corresponding to the fluid channel, a location corresponding to the first air gap, and a location corresponding to the second air gap;

etching the fluid channel comprises: etching into the waveguide layer, but not into the ARROW layer;

etching the first air gap comprises: etching into the waveguide layer, but not into the ARROW layer;

etching the second air gap comprises: etching into the waveguide layer, but not into the ARROW layer; and is

The method further comprises the following steps: the etch stop layer is dissolved.

15. The method of any one of claims 1 to 14, wherein:

the waveguide structure comprises a substrate layer coupled to the waveguide layer;

the method further comprises the following steps: etching into the substrate to create a third air gap adjacent to one or more of the fluid channel and the solid core waveguide, wherein the third air gap is configured to cause internal reflection of light propagating in one or more of the fluid channel and the solid core waveguide.

16. The method of claim 15, further comprising: disposing a lens element in the third air gap, wherein the lens element is configured to collect light escaping from the fluid channel into the third air gap.

17. The method of any of claims 15 to 16, wherein etching into the substrate to create the third air gap comprises: undercutting one or more of the fluid channel and the solid core waveguide.

18. The method of any one of claims 1 to 17, wherein the waveguide structure comprises micro-fabricated optical fiber alignment features.

19. The method of any of claims 1 to 18, further comprising: the waveguide layer is doped from a surface of the waveguide layer where etching is performed so that the waveguide layer has a gradient refractive index that is highest near the doped surface.

20. The method of claim 19, further comprising: providing a protective layer on the waveguide layer after doping the waveguide layer and before etching into the waveguide layer, wherein attaching the cladding layer to the waveguide layer comprises: attaching the cover layer to the protective layer.

21. The method of any one of claims 1 to 20, wherein:

etching the fluid channel comprises: performing dry etching;

etching the first air gap comprises: performing dry etching; and is

Etching the second air gap comprises: dry etching is performed.

22. The method of any of claims 1 to 21, further comprising: etching into the waveguide layer behind the end of the solid core waveguide, thereby forming the end of the solid core waveguide.

23. A waveguide structure, the structure comprising:

a waveguide layer comprising a fluid channel, a first air gap and a second air gap,

wherein the first air gap and the second air gap define a solid core waveguide in the waveguide layer between the first air gap and the second air gap; and

a cladding layer attached to the waveguide layer to enclose the fluidic channel.

24. The waveguide structure of claim 23, wherein the waveguide layer comprises a first oxide layer and a second oxide layer, wherein the first oxide layer is located on a first side of the second oxide layer and has a first refractive index, and the second oxide layer has a second refractive index lower than the first refractive index.

25. The waveguide structure of claim 24, wherein one or more of the fluid channel, the first air gap, and the second air gap extend at least partially through the first oxide layer and the second oxide layer.

26. A waveguide structure according to any one of claims 24 to 25, wherein:

the waveguide layer further comprises a third oxide layer located on a second side of the second oxide layer opposite the first side, wherein the third oxide layer has a third index of refraction lower than the first index of refraction; and is

One or more of the fluid channel, the first air gap, and the second air gap extend at least partially through the first oxide layer, the second oxide layer, and the third oxide layer.

27. A waveguide structure according to any one of claims 23 to 26, wherein the waveguide layer comprises one or more doped regions having a doped refractive index lower than the surrounding refractive index, wherein the one or more doped regions are adjacent the solid core waveguide.

28. The waveguide structure of claim 27, wherein the one or more doped regions are adjacent to the first and second air gaps.

29. The waveguide structure of any one of claims 27 to 28, wherein the one or more doped regions are adjacent to the fluid channel.

30. A waveguide structure according to any one of claims 23 to 29, wherein the waveguide layer comprises one or more doped regions having a higher doped refractive index than the surrounding refractive index, wherein the one or more doped regions form the solid core waveguide.

31. The waveguide structure of any one of claims 23 to 30, further comprising:

an ARROW layer;

wherein one or more of the fluid channel, the first air gap, and the second air gap extend at least partially through the waveguide layer without extending into the ARROW layer.

32. The waveguide structure of any one of claims 23 to 31, further comprising:

an ARROW layer; and

wherein the fluidic channel extends at least partially through the waveguide layer without extending into the ARROW layer; and is

Wherein one or more of the first and second air gaps extend at least partially through the waveguide layer and the ARROW layer.

33. The waveguide structure of any one of claims 23 to 32, further comprising a substrate layer coupled to the waveguide layer.

34. The waveguide structure of any one of claims 23 to 33, wherein the substrate layer comprises a third air gap adjacent to one or more of the fluid channel and the solid core waveguide, wherein the third air gap is configured to cause internal reflection of light propagating in one or more of the fluid channel and the solid core waveguide.

35. The waveguide structure of claim 34, wherein the third air gap comprises a lens element configured to collect light escaping from the fluid channel into the third air gap.

36. The waveguide structure of any one of claims 34 to 35, wherein the third air gap undercuts one or more of the fluid channel and the solid core waveguide.

37. A waveguide structure according to any one of claims 23 to 36, including micro-fabricated optical fibre alignment features.

38. A waveguide structure according to any one of claims 23 to 37, wherein the waveguide layer has a gradient index of refraction.

39. The waveguide structure of any one of claims 23 to 38, comprising a protective layer disposed on the waveguide layer, wherein one or more of the fluid channel, the first air gap, and the second air gap extend at least partially through the protective layer and the waveguide layer.

40. A method of fabricating a waveguide structure to form at least one solid core waveguide, the method comprising:

forming a first trench, a second trench and a third trench in the substrate layer;

forming an oxide layer from a machined substrate layer by oxidizing the machined substrate layer;

doping the oxide layer to create one or more doped regions having a doped index of refraction that is higher than an original index of refraction of the oxide layer, wherein doping the oxide layer:

creating a hollow core of a fluid passage at a location corresponding to the first groove; and

creating a solid core waveguide portion in the waveguide layer at a location corresponding to a region between the second trench and the third trench; and

attaching a capping layer to the doped oxide layer to close the fluid channel.

41. The method of claim 40, wherein the method further comprises: depositing a second oxide layer on the doped oxide layer prior to attaching the capping layer.

42. The method of any one of claims 40 to 41, wherein forming one or more of the first, second, and third trenches in the substrate layer comprises: machining the one or more grooves into the substrate layer.

43. The method of any one of claims 40 to 42, wherein the substrate layer comprises silicon.

44. A waveguide structure fabricated by a method comprising:

etching a fluid channel into a waveguide layer of the waveguide structure;

etching a first air gap and a second air gap into the waveguide layer,

wherein etching the first air gap and the second air gap creates a solid core waveguide in the waveguide layer between the first air gap and the second air gap; and

attaching a cover layer to the waveguide layer to close the fluidic channel.

Technical Field

The present disclosure relates generally to methods for fabricating waveguides, and more particularly to methods for fabricating two-dimensional waveguide structures such as optofluidic chips with solid core waveguides, fluid core channels, and/or fluid core waveguides.

Background

Waveguide structures such as optical chips and optofluidic chips are of critical importance in modern biomedical research. These waveguide structures may include solid core waveguides, fluid channels, and/or fluid core waveguides that may be disposed in the same plane as one another and may intersect one another in various configurations.

Known techniques for fabricating such structures require multiple fabrication steps. For example, known techniques for fabricating waveguide chips may include six or more photolithography steps, multiple etching steps, multiple deposition steps, and a sacrificial core removal process.

Disclosure of Invention

As described above, known techniques for manufacturing waveguide structures such as optical chips and optofluidic chips require multiple steps. Performing these various steps is difficult, complex, time consuming and expensive. For example, the alignment step introduces various opportunities for defects and imperfections in the waveguide structure due to misalignment. Furthermore, the sacrificial core removal process can be extremely time consuming. Furthermore, there is a need in the art of utilizing biosensor chips and waveguide structures to develop optimized chip and waveguide architectures, including by reducing the number of steps and processes used to manufacture the optimized chips and structures, to improve overall manufacturability, cost, yield, and reproducibility. Accordingly, there is a need for improved techniques for manufacturing waveguide structures including optical chips and optofluidic chips that are simpler, less difficult, less time consuming, and less expensive than known techniques.

Improved techniques are disclosed herein that may address one or more of the above needs. In some embodiments, a single lithography/etch process followed by a bonding process may replace the cumbersome and expensive series of steps required by the prior art, as described herein. The reduction in the total number of steps may allow for faster, more efficient, less complex, and less expensive production (e.g., manufacturability, cost, yield, reproducibility), including production on a commercial scale. Eliminating the alignment step may further improve quality control by preventing misalignment and defects that may result during conventional alignment processes. For example, these techniques may enable self-alignment and waveguide intersection with far fewer defects than those formed by conformal coating and etching. Furthermore, the techniques described herein may require fewer microfabrication steps, may create self-alignment of solid core waveguides with fluidic core channels (rather than one mask each), may create monolithic intersections between solid and fluidic cores, may allow direct fluidic integration (e.g., planar chip surfaces may enable bonding techniques and simpler fluidic interconnects), may eliminate the need for time-consuming sacrificial core removal, and may enable selection between a wider variety of materials than those compatible only with conventional methods, as compared to known methods.

In some embodiments, there is provided a first method for fabricating a waveguide structure to form at least one solid core waveguide from a waveguide layer, the first method comprising: etching a fluid channel into the waveguide layer; etching a first air gap and a second air gap into the waveguide layer, wherein etching the first air gap and the second air gap creates a solid core waveguide in the waveguide layer between the first air gap and the second air gap; and attaching a cladding layer to the waveguide layer to enclose the fluid channel.

In some embodiments of the first method, the waveguide layer includes a first oxide layer and a second oxide layer, wherein the first oxide layer is located on a first side of the second oxide layer and has a first refractive index, and the second oxide layer has a second refractive index lower than the first refractive index.

In some embodiments of the first method: etching the fluid channel includes etching into the second oxide layer and the first oxide layer at a time; etching the first air gap includes etching into the second oxide layer and the first oxide layer at a time; etching the second air gap includes etching into the second oxide layer and the first oxide layer at a time.

In some embodiments of the first method: the waveguide layer further comprises a third oxide layer located on a second side of the second oxide layer opposite the first side, wherein the third oxide layer has a third refractive index lower than the first refractive index; and etching the fluid channel comprises etching into the third oxide layer, the second oxide layer, and the first oxide layer at a time; etching the first air gap includes etching into the third oxide layer, the second oxide layer, and the first oxide layer at a time; etching the second air gap includes etching into the third oxide layer, the second oxide layer, and the first oxide layer at a time.

In some embodiments of the first method, the first method further comprises: the waveguide layer is doped to create one or more doped regions in the waveguide layer having a doping index lower than the surrounding index, wherein the one or more doped regions are adjacent to the solid core waveguide.

In some embodiments of the first method, the one or more doped regions are adjacent to the first air gap and the second air gap.

In some embodiments of the first method, the one or more doped regions are adjacent to the fluid channel.

In some embodiments of the first method, the first method further comprises: the waveguide layer is doped to create one or more doped regions in the waveguide layer having a higher doping index than the surrounding index, wherein the one or more doped regions form a solid core waveguide.

In some embodiments of the first method: the waveguide structure includes an ARROW (antiresonant reflecting optical waveguide) layer; etching the fluidic channel includes etching into the waveguide layer and not into the ARROW layer; etching the first air gap includes etching into the waveguide layer and not into the ARROW layer; etching the second air gap includes etching into the waveguide layer and not into the ARROW layer.

In some embodiments of the first method: the waveguide structure includes an ARROW layer; the waveguide structure includes an etch stop layer between the ARROW layer and the waveguide layer at a location corresponding to the fluid channel; the etching fluid channel includes: etching into the waveguide layer and not into the ARROW layer; dissolving the etch stop layer; etching the first air gap comprises etching into the waveguide layer and the ARROW layer at a time; etching the second air gap includes etching into the waveguide layer and the ARROW layer at a time.

In some embodiments of the first method: the waveguide structure includes an ARROW layer; etching the fluid channel includes performing dry etching followed by wet etching; etching the first air gap includes performing dry etching followed by performing wet etching; and etching the first air gap includes performing dry etching followed by performing wet etching.

In some embodiments of the first method: the waveguide structure includes an ARROW layer; etching the fluidic channel includes etching partially into the waveguide layer without etching through the waveguide layer to the ARROW layer; etching the first air gap comprises etching into the waveguide layer and the ARROW layer at a time; and etching the second air gap includes etching into the waveguide layer and the ARROW layer at a time.

In some embodiments of the first method: etching the first air gap comprises etching into the waveguide layer, the ARROW layer, and the substrate layer at a time; etching the second air gap includes etching into the waveguide layer, the ARROW layer, and the substrate layer at a time.

In some embodiments of the first method: the waveguide structure includes an ARROW layer below the waveguide layer; the waveguide structure includes an etch stop layer between the ARROW layer and the waveguide layer, the etch stop layer extending to a location corresponding to the fluid channel, a location corresponding to the first air gap, and a location corresponding to the second air gap; etching the fluidic channel includes etching into the waveguide layer and not into the ARROW layer; etching the first air gap includes etching into the waveguide layer and not into the ARROW layer; etching the second air gap includes etching into the waveguide layer and not into the ARROW layer; and the first method further comprises dissolving (dissolving) the etch stop layer.

In some embodiments of the first method: the waveguide structure includes a substrate layer coupled to a waveguide layer; the method also includes etching into the substrate to create a third air gap adjacent to one or more of the fluid channel and the solid core waveguide, wherein the third air gap is configured to cause internal reflection of light propagating in one or more of the fluid channel and the solid core waveguide.

In some embodiments of the first method, the first method further comprises: a lens element is disposed in the third air gap, wherein the lens element is configured to collect light escaping from the fluid channel into the third air gap.

In some embodiments of the first method, etching into the substrate to create the third air gap comprises: undercutting one or more of the fluid channel and the solid core waveguide.

In some embodiments of the first method, the waveguide structure includes a microfabricated fiber alignment feature.

In some embodiments of the first method, the first method further comprises: the waveguide layer is doped from a surface of the waveguide layer where etching is performed so that the waveguide layer has a gradient refractive index that is highest near the doped surface.

In some embodiments of the first method, the first method further comprises: providing a protective layer on the waveguide layer after doping the waveguide layer and before etching into the waveguide layer, wherein attaching the cladding layer to the waveguide layer comprises: attaching a cover layer to the protective layer.

In some embodiments of the first method: etching the fluid channel includes performing dry etching; etching the first air gap includes performing dry etching; etching the second air gap includes performing a dry etch.

In some embodiments of the first method, the first method further comprises: etching into the waveguide layer behind the end of the solid core waveguide to form the end of the solid core waveguide.

In some embodiments, there is provided a first waveguide structure comprising: a waveguide layer comprising a fluid channel, a first air gap, and a second air gap, wherein the first air gap and the second air gap define a solid core waveguide in the waveguide layer between the first air gap and the second air gap; and a cladding layer attached to the waveguide layer to enclose the fluid channel.

In some embodiments of the first waveguide structure, the waveguide layer comprises a first oxide layer and a second oxide layer, wherein the first oxide layer is located on a first side of the second oxide layer and has a first refractive index, and the second oxide layer has a second refractive index lower than the first refractive index.

In some embodiments of the first waveguide structure, one or more of the fluid channel, the first air gap, and the second air gap extend at least partially through the first oxide layer and the second oxide layer.

In some embodiments of the first waveguide structure: the waveguide layer further comprises a third oxide layer located on a second side of the second oxide layer opposite the first side, wherein the third oxide layer has a third refractive index lower than the first refractive index; one or more of the fluid channel, the first air gap, and the second air gap extend at least partially through the first oxide layer, the second oxide layer, and the third oxide layer.

In some embodiments of the first waveguide structure, the waveguide layer comprises one or more doped regions having a doped index of refraction lower than the surrounding index of refraction, wherein the one or more doped regions are adjacent to the solid core waveguide.

In some embodiments of the first waveguide structure, the one or more doped regions are adjacent to the first air gap and the second air gap.

In some embodiments of the first waveguide structure, the one or more doped regions are adjacent to the fluid channel.

In some embodiments of the first waveguide structure, the waveguide layer comprises one or more doped regions having a doped index of refraction higher than a surrounding index of refraction, wherein the one or more doped regions form a solid core waveguide.

In some embodiments of the first waveguide structure, the first waveguide structure further comprises: an ARROW layer; wherein one or more of the fluid channel, the first air gap, and the second air gap extend at least partially through the waveguide layer and not into the ARROW layer.

In some embodiments of the first waveguide structure, the first waveguide structure further comprises: an ARROW layer; and wherein the fluidic channel extends at least partially through the waveguide layer without extending into the ARROW layer; and wherein one or more of the first air gap and the second air gap extend at least partially through the waveguide layer and the ARROW layer.

In some embodiments of the first waveguide structure, the first waveguide structure further comprises a substrate layer coupled to the waveguide layer.

In some embodiments of the first waveguide structure, the substrate layer comprises a third air gap adjacent to one or more of the fluid channel and the solid core waveguide, wherein the third air gap is configured to cause internal reflection of light propagating in the one or more of the fluid channel and the solid core waveguide.

In some embodiments of the first waveguide structure, the third air gap comprises a lens element configured to collect light escaping from the fluid channel into the third air gap.

In some embodiments of the first waveguide structure, the third air gap undercuts one or more of the fluid channel and the solid core waveguide.

In some embodiments of the first waveguide structure, the first waveguide structure further comprises a microfabricated fiber alignment feature.

In some embodiments of the first waveguide structure, the waveguide layer has a graded index of refraction.

In some embodiments of the first waveguide structure, the first waveguide structure further comprises a protective layer disposed over the waveguide layer, wherein one or more of the fluid channel, the first air gap, and the second air gap extend at least partially through the protective layer and the waveguide layer.

In some embodiments, there is provided a second method for fabricating a waveguide structure to form at least one solid core waveguide, the second method comprising: forming a first trench, a second trench and a third trench in the substrate layer; forming an oxide layer from the machined substrate layer by oxidizing the machined substrate layer; doping the oxide layer to create one or more doped regions having a doped index of refraction that is higher than an original index of refraction of the oxide layer, wherein doping the oxide layer: creating a hollow core of a fluid passage at a location corresponding to the first groove; and creating a solid core waveguide section in the waveguide layer at a location corresponding to a region between the second trench and the third trench; and attaching a capping layer to the doped oxide layer to close the fluid channel.

In some embodiments of the second method, the second method further comprises: a second oxide layer is deposited on the doped oxide layer prior to attaching the capping layer.

In some embodiments of the second method, forming one or more of the first trench, the second trench, and the third trench in the substrate layer comprises: one or more grooves are machined into the substrate layer.

In some embodiments of the second method, the substrate layer comprises silicon.

In some embodiments, a second waveguide structure is provided, the second waveguide structure being made by a method comprising: etching a fluid channel into a waveguide layer of the waveguide structure; etching a first air gap and a second air gap into the waveguide layer, wherein etching the first air gap and the second air gap creates a solid core waveguide in the waveguide layer between the first air gap and the second air gap; and attaching a cladding layer to the waveguide layer to enclose the fluid channel.

In some embodiments, any one or more features of any one or more of the embodiments set forth above may be combined with each other and/or with other features or aspects of any of the methods, systems, techniques, or devices disclosed herein.

Drawings

Fig. 1A and 1B depict two schematic diagrams of a waveguide structure according to some embodiments.

Fig. 2A and 2B depict two schematic diagrams of a waveguide structure having a low index layer under a bonded cladding layer according to some embodiments.

Fig. 3A and 3B depict two schematic diagrams of a waveguide structure including a low index doped region defining one or more waveguides, according to some embodiments.

Fig. 4A and 4B depict two schematic diagrams of a waveguide structure including a high index doped region defining a waveguide, according to some embodiments.

Fig. 5A and 5B depict two schematic diagrams of a waveguide structure including an ARROW layer according to some embodiments.

Fig. 6A and 6B depict two schematic diagrams of a waveguide structure including an ARROW layer and an etch stop layer, according to some embodiments.

Fig. 7A and 7B depict two schematic diagrams of a waveguide structure including an ARROW layer and formed using a wet etch processing technique, according to some embodiments.

FIG. 8 depicts a schematic diagram of a waveguide structure including an ARROW layer and a variable depth etch, according to some embodiments.

Fig. 9A and 9B depict two schematic views of a waveguide structure including an anti-resonant reflective optical waveguide (ARROW) layer and an etch stop layer located below a plurality of trenches, according to some embodiments.

Fig. 10A and 10B depict two schematic diagrams of a waveguide structure including an air gap formed in a substrate layer, according to some embodiments.

Fig. 11A and 11B depict two schematic views of a waveguide structure including an air gap formed in a substrate layer and including a lens for light collection, according to some embodiments.

Fig. 12A and 12B depict two schematic diagrams of a waveguide structure including an undercut air gap formed in a substrate layer, according to some embodiments.

Fig. 13A and 13B depict two schematic diagrams of a waveguide structure including fiber alignment features according to some embodiments.

Fig. 14A-14D depict four schematic diagrams of a waveguide structure during various stages of a CMP-based trench fabrication method, according to some embodiments.

Fig. 15A and 15B depict two schematic diagrams of a waveguide structure including a doped oxide substrate, according to some embodiments.

Fig. 16A and 16B depict two schematic views of a waveguide structure including a doped oxide substrate and a capping layer (capping layer) under the bonded capping layer, according to some embodiments.

Fig. 17A and 17B depict two schematic views of a waveguide structure formed by oxidizing and doping a machined substrate layer to form a waveguide layer, according to some embodiments.

Fig. 18A and 18B depict two schematic views of a waveguide structure formed by oxidizing and doping a machined substrate layer to form a waveguide layer, according to some embodiments.

Fig. 19A and 19B depict two schematic views of a waveguide structure including an air gap formed in a substrate layer and including a lens for light collection and including an aperture layer (aperture layer), according to some embodiments.

Detailed Description

In some embodiments, a single lithography/etch process followed by a bonding process may replace the cumbersome and expensive series of steps required by the prior art, as described herein. For example, the waveguide structure (e.g., two-dimensional waveguide structure) may be formed by a chip comprising a substrate layer and a waveguide layer on top of the substrate layer. In some embodiments, the substrate layer may be formed of silicon or other suitable material, and the waveguide layer may be formed of one or more oxides (e.g., low temperature oxide, phosphorous doped oxide, silicon oxynitride, or other suitable material). In some embodiments, the thickness of the waveguide layer may be greater than or equal to 1 μm, 5 μm, 10 μm, or 20 μm. In some embodiments, the thickness of the waveguide layer may be less than or equal to 1 μm, 5 μm, 10 μm, or 20 μm. The materials used in the waveguide layers may be selected such that the materials efficiently transmit light and may form both the solid core of the solid core waveguide and the walls of the fluid channel and/or the walls of the fluid core waveguide.

After disposing (e.g., placing or depositing) the waveguide layer on the substrate layer, one or more etching steps may be performed to form one or more of the solid core waveguides and one or more of the fluidic channels (which may also be fluidic core waveguides in some embodiments). To form the fluidic channel, a hollow core of the channel may be etched from the waveguide layer.

In some embodiments, the size of the fluid channel may be varied to affect the flow rate of the fluid through the fluid channel. In some embodiments, the flow of fluid through the fluid channel may be caused by one or more of vacuum, positive pressure, electro-osmosis, and/or electrophoresis. In some embodiments, the geometry of the fluid channel may be formed to induce flow focusing via sheath flow (sheath flow). In some embodiments, the channel fluidic channel can have a height and/or width of less than or equal to 0.25 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 25 μm, 50 μm, 100 μm, 250 μm, 500 μm, or 1000 μm. In some embodiments, the channel fluidic channel can have a height and/or width greater than or equal to 0.25 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 25 μm, 50 μm, 100 μm, 250 μm, 500 μm, or 1000 μm. In some embodiments, the flow rate through the fluidic channel can be less than or equal to 0.005 μ L/min, 0.01 μ L/min, 0.1 μ L/min, 1 μ L/min, 10 μ L/min, 100 μ L/min, or 500 μ L/min. In some embodiments, the flow rate through the fluidic channel can be greater than or equal to 0.005 μ L/min, 0.01 μ L/min, 0.1 μ L/min, 1 μ L/min, 10 μ L/min, 100 μ L/min, or 500 μ L/min.

To form the solid core waveguide, air gaps may be etched from the waveguide layer on each side of the solid core waveguide such that the solid core waveguide is formed from the remaining material of the waveguide layer that remains between the air gaps. In some embodiments, the etching step may include dry etching, such as reactive ion etching, deep reactive ion etching, and/or neutral loop discharge etching; in some embodiments, the etching step may include a wet etch, such as an etch with buffered hydrofluoric acid. In some embodiments, in addition to etching the air gap to define the region on each side of the solid core waveguide, the etching process may further comprise: the region at the end of the solid core waveguide is etched to form the end of an optical waveguide (e.g., an optical facet) into which light can be coupled.

After etching the waveguide layer to form the solid core waveguide and the fluidic channel, a capping layer may be applied to the top of the waveguide layer to close one or more of the open top sides of the fluidic channel and/or to close the air gap. In some embodiments, the cover layer may include a bonded glass, ARROW layer, or total internal reflection coated material (e.g., low index material such as TEFLON AF) or metal coated material. In some embodiments, the thickness of the capping layer may be less than or equal to 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 150 μm, or 200 μm, 300 μm, or 500 μm. In some embodiments, the capping layer may be greater than or equal to 1 μm, 5 μm, or 10 μm, 50 μm, 100 μm, 150 μm, or 200 μm, 300 μm, or 500 μm. In some embodiments, the cover layer may be attached to the waveguide layer (or another layer of the waveguide structure, as discussed further below) by permanent or non-permanent bonding, adhesive bonding, or other suitable means.

After the etching and attachment of the cover layer is completed, the fluid channel may be filled with a fluid (e.g., gas and/or liquid), such as a gas or liquid containing an analyte to be excited by excitation light propagating along the solid core waveguide and incident on the fluid channel. In some embodiments, emissions from analytes in a fluidic channel can be collected out-of-plane (e.g., by a photodetector above or below) or in-plane (e.g., by being directed by the fluidic channel to an in-plane photodetector when the fluidic channel is a fluidic core waveguide, or by capturing the emissions by a solid core waveguide structure without the use of a fluidic core waveguide).

In some embodiments, the performance of a fluidic channel as a fluid core waveguide (e.g., for in-plane detection of emitted light) may be improved by reducing the wall thickness, by reducing the average refractive index of the cladding material, or by etching away some of the substrate layers below the channel, as discussed further below.

Fig. 1A and 1B depict two schematic views of a waveguide structure 100 according to some embodiments. Fig. 1A shows a cross-sectional view from two angles of a waveguide structure 100, wherein the two views are divided by a dashed line indicating a 90 ° angle 102. Fig. 1B shows a top view of the waveguide structure 100.

As shown in fig. 1A, the waveguiding layer 104 may be formed of one or more oxide layers. In some implementations, low refractive index oxide layer 106 may be disposed atop substrate (e.g., silicon) layer 108, and high refractive index oxide layer 110 may be disposed atop low refractive index oxide layer 106. The two oxide layers may together form the waveguiding layer 104. As light 112 propagates through high index oxide layer 110, it may be internally reflected along solid core waveguide 114 through air gap 116 and/or low index oxide layer 106. In some embodiments, both low index oxide layer 106 and substrate layer 108 may be replaced by a low index substrate layer.

As shown in fig. 1A, the etching step to form air gap 116 and fluid channel 118 may be performed such that etching into and/or through high refractive index oxide layer 110 and low refractive index oxide layer 106 is simultaneous. That is, rather than etching the oxide layers separately and then aligning the gaps/vias etched into the oxide layers, etching may be performed after the layers have been bonded to each other, thereby achieving self-alignment. As shown in the example of fig. 1, in some implementations, the channels 118 and/or air gaps 116 may be formed by etching completely through the high index oxide layer 110 from above and partially into the low index oxide layer 106 from above. In some embodiments, waveguide structure 100 may include a cladding layer 120, which cladding layer 120 may be applied to the top of waveguide layer 104 to enclose the open top side of fluid channel 118 and/or to enclose one or more air gaps 116.

In some embodiments of any of the waveguide structures disclosed herein, one or more of the waveguide layers may be placed or deposited on top of another of these layers. In some embodiments, one or more layers may be deposited via sputtering, spin-coating, Plasma Enhanced Chemical Vapor Deposition (PECVD), Low Pressure Chemical Vapor Deposition (LPCVD), electron beam evaporation, and/or any other deposition method.

Because there is only one lithography step, it may be very easy to create more complex waveguide structures using this method and expose individual dies (e.g., e-beam defined features) for the process. Furthermore, in this workflow, there is no need to align the mask between manufacturing steps.

In some embodiments of waveguide structure 100 and/or other waveguide structures discussed herein, the refractive index of the high refractive index oxide (e.g., layer 110) can be less than or equal to 1, 2, 3, or 4. In some embodiments of fig. 1 and/or other waveguide structures discussed herein, the refractive index of the high refractive index oxide (e.g., layer 110) can be greater than or equal to 1, 2, 3, or 4.

In some embodiments of waveguide structure 100 and/or other waveguide structures discussed herein, the low refractive index oxide (e.g., layer 106) can have a refractive index less than or equal to 1, 2, 3, or 4. In some embodiments of fig. 1 and/or other waveguide structures discussed herein, the low refractive index oxide (e.g., layer 106) can have a refractive index greater than or equal to 1, 2, 3, or 4.

In some embodiments of waveguide structure 100 and/or other waveguide structures discussed herein (e.g., see fig. 15 and 16 below), the doped oxide can have a refractive index less than or equal to 1, 2, 3, or 4. In some embodiments of fig. 1 and/or other waveguide structures discussed herein, the doped oxide may have a refractive index greater than or equal to 1, 2, 3, or 4.

In some embodiments, the thickness of the oxide layer (e.g., low refractive index oxide layer 106) adjacent to the substrate layer may be less than or equal to 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, or 50 μm. In some embodiments, the thickness of the oxide layer (e.g., low refractive index oxide layer 106) adjacent to the substrate layer can be greater than or equal to 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, or 50 μm. In some embodiments, a thicker oxide layer (e.g., low refractive index oxide layer 106) adjacent to the substrate layer may improve the guiding characteristics of the waveguide and/or reduce background photoluminescence from adjacent silicon/substrate material.

In some embodiments, the thickness of the core oxide layer (e.g., high refractive index oxide layer 110) may be less than or equal to 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 15 μm. In some embodiments, the thickness of the core oxide layer (e.g., high refractive index oxide layer 110) may be greater than or equal to 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 15 μm.

Fig. 2A and 2B depict two schematic diagrams of a waveguide structure 200 having a low index layer 206 under a bonded cladding layer 220, according to some embodiments. Fig. 2A shows a cross-sectional view from two angles of the waveguide structure 200, wherein the two views are divided by a dashed line indicating a 90 ° angle 202. Fig. 2B shows a top view of the waveguide structure 200.

The waveguide structure 200 shown in fig. 2 may share any one or more characteristics in common with the waveguide structure 100 shown in fig. 1, and may differ from the structure 100 shown in fig. 1 in that: waveguide layer 204 of the structure in fig. 2 may include an additional low index oxide layer 222 atop high index oxide layer 210 and below cladding layer 220. In some embodiments, the second low refractive index oxide layer 222 may be disposed (e.g., placed or deposited) on top of the other oxide layer after the other oxide layer is disposed (e.g., placed or deposited). As light 212 propagates through high index oxide layer 210, it may be internally reflected along solid core waveguide 214 by air gap 216, low index oxide layer 206, and/or additional low index oxide layer 222.

In some embodiments, the thickness of second low refractive index oxide layer 222 may be less than or equal to 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 15 μm. In some embodiments, the thickness of second low refractive index oxide layer 222 may be greater than or equal to 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 15 μm.

In some embodiments, the etching step that forms the air gap 216 and the fluid channel 218 may be performed such that etching into and/or through the high refractive index oxide layer 210 and the two low refractive index oxide layers 206, 222 is performed simultaneously. That is, rather than etching the oxide layers separately and then aligning the gaps/vias etched into the oxide layers, etching may be performed after the layers have been bonded to each other, thereby achieving self-alignment. As shown in the example of waveguide structure 200, in some embodiments, channels 218 and/or air gaps 216 may be formed by etching completely through upper low index oxide layer 222 from above, completely through high index oxide layer 210 from above, and partially into low index oxide layer 206 from above. In some embodiments, the etch that forms the fluid channel 218 may cut completely through the waveguide layer 204 and partially into the substrate layer 208 (as shown by the dashed outline 224).

The presence of the bottom and top low index layers 206, 222 (or alternatively ARROW layers) may create a well-defined waveguide, and the cladding layer 220 may enable the use of any type of material to seal the liquid channel 218 without significantly interfering with the optical properties required for waveguide in the solid core waveguide 214 and, in some embodiments, the fluid core waveguide.

Fig. 3A and 3B depict two schematic diagrams of a waveguide structure 300 including a low index doped region 326 defining one or more waveguides, according to some embodiments. Fig. 3A shows a cross-sectional view from two angles of the waveguide structure 300, wherein the two views are divided by a dashed line indicating a 90 ° angle 302. Fig. 3B shows a top view of the waveguide structure 300.

The waveguide structure 300 shown in fig. 3 may share any one or more characteristics in common with the waveguide structure 100 shown in fig. 1, and may differ from the structure 100 shown in fig. 1 in that: instead of, or in the alternative to, defining the solid core waveguide 314 and/or the fluid core waveguide by etching the air gap 316, dopant diffusion through a photomask may be used to define a region 326 in the waveguide layer 304 having a lower index of refraction than other regions in the waveguide layer 304.

In some embodiments, dopant diffusion may include ion diffusion, ion exchange, and/or ion implantation. In some embodiments, the ions used for dopant diffusion may include He +, N +, O +, Si +, P +, Ti +, Ge +, or any one or more of the ions indicated in: righini, GC&Chiappini,A.Glass optical waveguides:a review of fabrication techniques.OE,OPEGAR 53,071819(2014)；Optical Waveguides branched by Ion Implantation/Irradation of guez, O. et al: ion implantation (inetch, 2012); and/or Chen f, Wang, x, -L.&Wang, K. -M.development of ion-implanted optical waveguides in optical materials: optical Materials 29, 1523-. Thus, as shown in the top view of fig. 3b, the solid core waveguide 314 may be defined by a region between two doped regions 326. In some implementations, using dopants to define the waveguide can create a structure 300 with less refraction and scattering of light 312 than structures that rely on etching to form a solid core waveguide 314, which can reduce the background signal of the chip.

In some embodiments, dopant diffusion in waveguide layer 304 may also be used to define regions beside, below, and/or above the waveguide, including solid core waveguide 314 and/or fluid core waveguide. In some embodiments, waveguide layer 304 includes a low index oxide layer 306 and a high index oxide layer 310. A low index oxide layer 306 may be disposed on top of a substrate (e.g., silicon) layer 308, and a high index oxide layer 310 may be disposed on top of the low index oxide layer 306. In some embodiments, additional doped regions 328 may be included to define specific modes in the waveguide or to generate other optical phenomena. The additional doped regions 328 may be located within the low index oxide layer 306 (disposed on the substrate layer 308) and/or within the high index oxide layer 310 (disposed below the cap layer 320).

In some embodiments, dopant diffusion may be performed before one or more etching steps, and in some embodiments, dopant diffusion may be performed after one or more etching steps.

Fig. 4A and 4B depict two schematic diagrams of a waveguide structure 400 including a high index doped region defining a waveguide, according to some embodiments. Fig. 4A shows a cross-sectional view from two angles of the waveguide structure 400, wherein the two views are divided by a dashed line indicating a 90 ° angle 402. Fig. 4B shows a top view of the waveguide structure 400.

The waveguide structure 400 in fig. 4 may share any one or more characteristics in common with the waveguide structure 300 shown in fig. 3. Like the waveguide structure 300 shown in fig. 3, the waveguide structure 400 shown in fig. 4 may include one or more waveguides created and defined by dopant diffusion (e.g., dopant diffusion through a photomask). Although the structure 300 shown in fig. 3 may be created using dopant diffusion that defines doped regions 326 having a lower index of refraction than surrounding regions, the structure 400 shown in fig. 4 may alternatively be created using dopant diffusion that defines doped regions having a higher index of refraction than surrounding regions. In some embodiments, germanium or other suitable ions (e.g., one or more of the ions indicated above) may be used to create the high index region via doping. It should be noted that in some embodiments, the refractive index change created by doping waveguide layer 404 may include an instantaneous spatial change (e.g., a step change) in refractive index and/or may include a spatial gradual increase or decrease in refractive index.

Thus, as shown in the top view of fig. 4B, the solid core waveguide 414 may be defined by the doped region itself, which may have a higher index of refraction than the undoped oxide in the waveguide layer 404. In some implementations, using dopants to define the waveguide can create a less refractive and scattering structure 400 with light 412 than a structure that relies on etching to form a solid core waveguide 414, which can reduce the background signal of the chip. In some implementations, waveguide layer 404 can include an oxide layer 406 disposed atop a substrate layer 408. Waveguide layer 404 may also include air gap 416 and fluid channel 418. In some embodiments, cladding layer 420 may be disposed on top of waveguide layer 404.

In some embodiments, dopant diffusion may be performed before one or more etching steps, and in some embodiments, dopant diffusion may be performed after one or more etching steps.

Fig. 5A and 5B depict two schematic diagrams of a waveguide structure 500 including an ARROW layer 530, according to some embodiments. Fig. 5A shows a cross-sectional view from two angles of a waveguide structure 500, wherein the two views are divided by a dashed line indicating a 90 ° angle 502. Fig. 5B shows a top view of the waveguide structure 500.

The waveguide structure 500 shown in fig. 5 may share any one or more characteristics in common with the waveguide structure 100 shown in fig. 1, and may differ from the structure 100 shown in fig. 1 in that: the structure 500 also includes an ARROW layer 530 above the substrate 508 and below the waveguide layer 504. In some implementations, the ARROW layer 530 can be disposed (e.g., placed or deposited) on top of the substrate layer 508, and then the waveguide layer 504 can be disposed (e.g., placed or deposited) on top of the ARROW layer 530. In some embodiments using an ARROW layer 530 below the waveguide layer 504, the waveguide layer 504 may have a constant index of refraction from top to bottom rather than being composed of multiple different oxide layers having different indices of refraction.

As shown in the cross-sectional view of fig. 5A, in some embodiments, the channels 518 and/or air gaps 516 may be formed by etching partially into the waveguide layer 504 without completely etching through to prevent etching into the ARROW layers 530 and compromising their optical properties. In some implementations, the solid core waveguide 514 can be defined by etching. In some embodiments, a cladding layer 520 may be disposed atop the waveguide layer 504.

In some embodiments, the total thickness (e.g., total stack thickness) of the ARROW layer 530 may be less than or equal to 0.1 μm, 0.2 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, or 15 μm. In some embodiments, the total thickness (e.g., total stack thickness) of the ARROW layer 530 may be greater than or equal to 0.1 μm, 0.2 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, or 15 μm. The total thickness of the ARROW layers 530 may vary depending on the number of alternating layers and/or the desired guiding properties (e.g., for guiding light 512).

Fig. 6A and 6B depict two schematic diagrams of a waveguide structure 600 including an ARROW layer 630 and an etch stop layer 632, according to some embodiments. Fig. 6A shows a cross-sectional view from two angles of the waveguide structure 600, wherein the two views are divided by a dashed line indicating a 90 ° angle 602. Fig. 6B shows a top view of the waveguide structure 600.

The waveguide structure 600 shown in fig. 6 may differ from the structure 500 shown in fig. 5 in that: structure 600 also includes an etch stop layer 632 above the ARROW layer 630 and below the waveguide layer 604. In some embodiments, etch stop layer 632 may be a partial etch stop layer positioned below the area to be etched away to form fluid channel 618. In this manner, the etching step that forms the air gap 616 may be allowed to etch completely through the waveguide layer 604, into and/or through the ARROW layer 630, and into the substrate layer 608; however, the etching step that forms etching fluid channel 618 may prevent etching into or through ARROW layer 630 by etch stop layer 632. Thus, the ARROW layer 630 may be protected and retained at locations below the fluid channel 618, whereas the ARROW layer 630 may be etched through at other locations on the structure 600.

In some embodiments, after the step of etching the fluid channels 618, the local etch stop layer 632 may be dissolved, for example, by wet etching, or the local etch stop layer 632 may be otherwise removed such that the hollow core of the fluid channels 618 directly abuts the ARROW layer 630. In some implementations, the etch stop layer 632 can be left in place, for example, when the etch stop layer 632 is compatible with the desired optical properties of the ARROW layer 630.

In some embodiments, etch stop layer 632 may comprise a metal, a dielectric material, a polycrystalline material, and/or other suitable materials. In some embodiments, the material for the etch stop layer 632 may be selected such that the material has a sufficiently different etch rate when compared to the etch rate of the one or more materials of the waveguide layer 604.

In some embodiments, the thickness of etch stop layer 632 may be less than or equal to 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm, or 10 μm. In some embodiments, the thickness of etch stop layer 632 may be greater than or equal to 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm, or 10 μm.

Fig. 7A and 7B depict two schematic views of a waveguide structure 700 that includes an ARROW layer 730 and is formed using a wet etch processing technique, according to some embodiments. Fig. 7A shows a cross-sectional view from two angles of a waveguide structure 700, where the two views are divided by a dashed line indicating a 90 ° angle 702. Fig. 7B shows a top view of the waveguide structure 700.

The waveguide structure 700 shown in fig. 7 may share any one or more characteristics in common with the waveguide structure 500 shown in fig. 5, and may differ from the structure 500 shown in fig. 5 in that: for each air gap 716 and fluid channel 718, after the first etching step (e.g., a coarse, deep etching step), a second etching step may be performed to etch completely through the waveguide layer 704 and down to the ARROW layer 730 (but not into the ARROW layer 730). In some embodiments, the first etching step may be a deep etch and the second etching step may be a wet etch. In some embodiments, a second etching step may be used to further etch down 734 and/or further etch to the sides of the etched gap 716 or channel 718. In some embodiments, the outermost layer (e.g., top layer or bottom layer) of the ARROW layer 730 may be an etch stop ARROW configured to prevent a wet etch step from etching into the ARROW layer 730 and damaging the ARROW layer 730. By selecting the outermost ARROW layer as an effective etch stop for an etching process such as wet etching, and by applying a subsequent wet etching after deep etching, an undamaged ARROW layer 730 can be obtained directly below the fluid channel 718.

In some embodiments, to obtain relatively vertical sidewalls of the channels 718 and/or air gaps 716, etching may be performed to a substantial depth such that the tops of the profiles of the channels 718 and/or air gaps 716 are relatively vertical.

FIG. 8 depicts a schematic diagram of a waveguide structure 800 including an ARROW layer 830 and a variable depth etch, according to some embodiments. Fig. 8 shows a cross-sectional view from two angles of the waveguide structure 800, wherein the two views are divided by a dashed line indicating a 90 ° angle 802.

The waveguide structure 800 shown in fig. 8 may share any one or more characteristics in common with the waveguide structure 600 shown in fig. 6, and may differ from the structure 600 shown in fig. 6 in that: the structure 800 in fig. 8 may not have a local etch stop layer (or any etch stop layer, such as layer 632). Thus, during etching, even if the etching is not stopped by the etch stop layer (e.g., layer 632), the etching that forms the liquid channel 818 can be stopped without completely cutting through the waveguide layer 804 and into the ARROW layer 830.

Fig. 9A and 9B depict two schematic diagrams of a waveguide structure 900 including an ARROW layer 930 and an etch stop layer 932 located below a plurality of trenches, according to some embodiments. Fig. 9A shows a cross-sectional view. Fig. 9B shows a top view of the waveguide structure 900.

The waveguide structure 900 shown in fig. 9 may share any one or more characteristics in common with the waveguide structure 600 shown in fig. 6, and may differ from the structure 600 shown in fig. 6 in that: the etch stop layer 932 included in the structure 900 may not be positioned solely in correspondence with the fluid channel 918. Alternatively, the etch stop layer 932 may extend to a region below one or more other etches (e.g., one or more air gaps 916 etched out of the waveguide layer 904). Thus, the non-local etch stop layer 932 may prevent the etch that forms the fluid channels 918 and the etch that forms the one or more air gaps 916 from extending into the ARROW layer 930.

In some embodiments, the etch stop layer 932 may be completely or partially dissolved or otherwise removed after one or more etching steps. In some implementations, the etch stop layer 932 may remain present under the solid core waveguide 914 (e.g., even if the etch stop layer 932 is removed from the region where the etching is performed at the fluid channel 918 and the air gap 916), and thus, the etch stop layer 932 may be transparent such that it does not block the light 912 in the solid core waveguide 914 from propagating into the ARROW layer 930. In some embodiments, transparent etch stop layer 932 may include one or more oxides. (in some embodiments, the opaque etch stop layer 932 may include one or more metals, and in some embodiments, the opaque etch stop layer 932 may be removed from the waveguide structure 900 using a secondary process step, such as an additional etch step.)

In some embodiments, the thickness of the transparent etch stop layer 932 may be less than or equal to 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 15 μm. In some embodiments, the thickness of the transparent etch stop layer 932 may be greater than or equal to 0.5 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 10 μm, or 15 μm.

Fig. 10A and 10B depict two schematic views of a waveguide structure 1000 including an air gap 1036 formed in a substrate layer 1008, according to some embodiments. Fig. 10A shows a cross-sectional view from two angles of the waveguide structure 1000, where the two views are divided by a dashed line indicating a 90 ° angle 1002. Fig. 10B shows a top view of the waveguide structure 1000.

The waveguide structure 1000 shown in fig. 10 may share any one or more characteristics in common with the waveguide structure 100 shown in fig. 1, and may differ from the structure 100 shown in fig. 1 in that: in addition to performing a top-down etch to form the fluid channels 1018 and the solid core waveguide 1014 in the waveguide layer 1004, a bottom-up etch may be performed to remove a portion of the substrate layer 1008 and expose an underside of the waveguide layer 1004 to one or more air gaps 1036 below the fluid channels 1018 and/or the solid core waveguide 1014. By creating one or more air gaps 1036 below the fluid channel 1018 and/or the solid core waveguide 1014, the need for an ARROW layer (e.g., layer 930) or a low index oxide layer may be eliminated, as the air gaps 1036 carved out of the substrate layer 1008 may themselves prevent light 1012 in the solid core waveguide 1014 and/or the fluid channel 1018 (which may act as a flow core waveguide) from leaking down the waveguide 1014/channel 1018.

In some implementations, etching into the substrate layer 1008 (e.g., by etching into a side of the substrate layer 1008 opposite the waveguide layer 1004 as shown in fig. 10) can additionally or alternatively be used to form one or more fluidic channels and/or other structures for routing fluids through the substrate layer 1008.

In some implementations, etching into the substrate layer 1008 (e.g., by etching into a side of the substrate layer 1008 opposite the waveguide layer 1004 as shown in fig. 10) can additionally or alternatively be used to form a structure on the waveguide structure 1000 for physically positioning the waveguide structure 1000. In some embodiments, microfabrication of the substrate 1008 can be used to form one or more kinematic structures. In some implementations, one or more structures formed via etching into the substrate layer 1008 can be used to attach to and/or physically interact with a physical positioning and/or alignment system. In some implementations, one or more structures formed via etching into the substrate layer 1008 can be filled with, can receive, and/or can be otherwise attached to magnetic material and/or one or more magnetic components for kinematic applications.

Fig. 11A and 11B depict two schematic diagrams of a waveguide structure 1100 including an air gap 1136 formed in a substrate layer 1108 and including a lens 1138 for light collection, according to some embodiments. Fig. 11A shows a cross-sectional view from two angles of the waveguide structure 1100, where the two views are divided by a dashed line indicating a 90 ° angle 1102. Fig. 11B shows a top view of the waveguide structure 1100.

The waveguide structure 1100 shown in fig. 11 may share any one or more characteristics in common with the waveguide structure 1000 shown in fig. 10, and may differ from the structure 1000 shown in fig. 10 in that: the structure 1100 may also include one or more lenses, for example, for out-of-plane excitation light collection. As shown, one or more lenses (e.g., lens 1138) may be included in the cover layer 1120 or attached to the cover layer 1120, for example, by adhesive bonding, permanent or non-permanent bonding, or by fabrication within the cover layer 1120 itself, for collecting excitation light 1112 from the fluid channel 1118 at the top. Alternatively or additionally, one or more lenses (e.g., lens 1140) may be attached below the fluid channel 1118 after etching the lower air gap 1136 from the substrate 1108 for collecting the excitation light 112 from the fluid channel 1118 at the lower side. In some implementations, one or more lenses 1138, 1140 can be formed from a polymeric material, a dielectric material, glass, or any other suitable material.

Fig. 12A and 12B depict two schematic diagrams of a waveguide structure 1200 including an undercut air gap 1242 formed in a substrate layer 1208, according to some embodiments. Fig. 12A shows a cross-sectional view from two angles of the waveguide structure 1200, where the two views are divided by a dashed line indicating a 90 ° angle 1202. Fig. 12B shows a top view of the waveguide structure 1200.

The waveguide structure 1200 shown in fig. 12 may share any one or more common characteristics with the waveguide structure 1000 shown in fig. 10, and may differ from the structure 1000 shown in fig. 10 in that: the fluid channel 1218 and/or the air gap 1242 below the solid core waveguide 1214 may not be created by etching the substrate layer 1208 from below, but rather by performing an under-etch (e.g., a potassium hydroxide (KOH) etch) to cut into and below the solid core waveguide 1214 and/or the fluid channel 1218 from the air gap 1216 initially etched into the waveguide layer 1204. In some embodiments, an under-etch may be performed in the bridge portion, for example to prevent collapse of the suspension structure.

Fig. 13A and 13B depict two schematic views of a waveguide structure 1300 including optical fiber alignment features 1344 according to some embodiments. Fig. 13A shows a cross-sectional view from two angles of the waveguide structure 1300, where the two views are divided by a dashed line indicating a 90 ° angle 1302. Fig. 13B shows a top view of the waveguide structure 1300.

The waveguide structure 1300 shown in fig. 13A and 13B may share any one or more characteristics in common with the waveguide structure 100 shown in fig. 1, and may differ from the structure 100 shown in fig. 1 in that: the structure 1300 may incorporate one or more conventional optical fibers, for example, for guiding the excitation light 1312. For example, instead of creating a solid core waveguide by etching an air gap into the waveguide layer 1304, an optical fiber 1346 may be used to guide the light 1312 to the fluid channel 1318 (which may be formed in the same manner as discussed elsewhere herein). In some embodiments, an optical fiber 1346 may be used to guide the excitation light 1312 to a solid core waveguide formed as discussed elsewhere herein.

Fig. 14A-14D depict four schematic views of a waveguide structure 1400 during various stages of a CMP (chemical mechanical polishing) -based trench fabrication method, according to some embodiments. The waveguide structure 1400 shown in fig. 14 may share any one or more characteristics in common with the waveguide structure 100 shown in fig. 1. Unlike some other embodiments discussed herein, the technique shown in fig. 14 may depend largely on machining one or more features into the silicon substrate 1408 (or other non-oxide substrate) in addition to or instead of etching into one or more oxides. In some embodiments, waveguide structure fabrication techniques that rely on machining into silicon or other substrate material may be simpler, faster, more efficient, and less expensive than techniques that rely primarily or exclusively on etching into oxide, because machining silicon may be a simpler and more standardized process than etching into oxide.

As shown in fig. 14A, the silicon substrate 1408 may be machined (e.g., micromachined) to create two intersecting grooves (one groove is shown on the right side 1448 of the 90 degree angle and the other groove is shown on the left side 1450 of the 90 degree angle 1402). One or more oxides may then be deposited on the machined silicon substrate 1408 so that the machined trenches 1448, 1450 may be filled with oxide 1406. After disposing (e.g., depositing or placing) the oxide 1406, the fluid channels 1418 may be etched into the oxide 1406 as shown to the right of the 90 degree angle 1402. (alternatively, in some embodiments, the oxide portion forming fluid channel 1418 may be formed by oxidizing etched silicon trench 1448, for example as discussed below with reference to fig. 17 and 18).

As shown in fig. 14B, the following oxide 1406 disposed (e.g., deposited or placed) on the substrate 1408 may then be removed: the oxide 1406 is not within one of the trenches 1448 or 1450 machined in the substrate 1406. In some embodiments, the oxide 1406 may be removed by CMP, and in some embodiments, the oxide 1406 may be stripped.

As shown in fig. 14C, the silicon substrate 1408 surrounding the trench 1448 into which the fluid channel 1418 is etched may then be removed, for example by KOH etching. In some embodiments, substrate 1408 can be etched away from region 1442, which region 1442 can include one or both sides and a portion of the region underlying oxide 1406 forming fluid channel 1418 (e.g., by under-etching).

As shown in fig. 14D, the silicon substrate 1408 of the oxide-filled trench 1450 surrounding the left side of the 90 degree angle 1402 may then be removed, for example, by a KOH etch. In some embodiments, substrate 1408 can be etched away from region 1452, which region 1452 can include one or both sides and a portion of the region under oxide 1406 forming (e.g., by an underetch) oxide-filled trench 1450.

Finally, as shown in fig. 14D, a cover layer 1420 may be added to close the fluid channel 1418. The cover layer 1420 may share any one or more features with other cover layers discussed elsewhere herein (e.g., cover layer 120).

Thus, the oxide 1454 shown on the left side of the 90 degree angle 1402 can serve as a solid core waveguide for the light 1412, and the etched oxide 1456 shown on the right side of the 90 degree angle can serve as a fluid channel 1418 and/or a fluid core waveguide that intersects the solid core waveguide (e.g., oxide 1454).

Fig. 15A and 15B depict two schematic views of a waveguide structure 1500 including a doped oxide substrate 1508, according to some embodiments. Fig. 15A shows a cross-sectional view from two angles of the waveguide structure 1500, where the two views are divided by a dashed line indicating a 90 ° angle 1502. Fig. 15B shows a top view of the waveguide structure 1500.

The waveguide structure 1500 shown in fig. 15 may share any one or more features in common with the waveguide structure 100 shown in fig. 1, and may differ from the waveguide structure 100 shown in fig. 1 and other waveguide structures shown herein (e.g., structures 200-1400) in that: the structure may be formed from a monolithic oxide substrate 1508 (e.g., a quartz glass wafer, Borofloat, BK7, fused silica, or single crystal quartz) rather than including a substrate (e.g., silicon) layer (e.g., layer 108) that is different from a waveguide (e.g., oxide) layer (e.g., layer 104). In some implementations, the oxide substrate 1508 can be doped by ions (e.g., see discussion of ion doping above) near a surface (e.g., top surface 1558) of the substrate 1508 to create a graded index of refraction in the oxide such that the index of refraction is higher in the oxide substrate 1508 near the doped surface (e.g., top surface 1558) than in the oxide substrate 1508 away from the doped surface (e.g., top surface 1558). In some implementations, the entire surface of the oxide substrate 1508 (e.g., the top surface 1558) can be subjected to blanket doping rather than using a mask to dope only certain areas. An etching step as discussed elsewhere herein may then be performed by etching into the doped surface (e.g., top surface 1558) of oxide substrate 1508 to form fluid channels 1518 and air gaps 1516. Due to the gradient index of refraction, excitation light 1512 in a fluid-core waveguide (e.g., fluid channel 1518) defined between etched air gaps may be prevented from leaking down into the low index portion of oxide substrate 1508. While gradient refractive indices are discussed above, in some embodiments, the refractive index may also vary in one or more spatial step functions according to one or more spatial curves and/or according to one or more spatial gradients.

In some embodiments of fig. 15 and/or other waveguide structures discussed herein, the doped oxide (e.g., layer 1508) can have a refractive index less than or equal to 1, 2, 3, or 4. In some embodiments of fig. 15 and/or other waveguide structures discussed herein, the doped oxide (e.g., layer 1508) can have a refractive index greater than or equal to 1, 2, 3, or 4.

In some embodiments, by using a blanket doping technique over the entire oxide substrate 1508, the deposition step can be minimized and the background reduced due to the pure waveguide material. Furthermore, in some implementations, using dopants to define the waveguide (e.g., solid core waveguide 1514) may potentially cause less refraction and scattering of the light 1512, which may be an advantage in reducing the background signal of the chip.

In some embodiments, light 1512 in the fluidic channel 1518 may be able to leak out of the channel and down into the oxide substrate 1508, so the fluidic channel 1518 may only function as a channel and not as a fluid core waveguide. However, in some implementations, a deep etch (or an undercut etch) may be performed on the underside of the substrate 1508 to create an air gap below the fluidic channel 1518 and to cause the fluidic channel 1518 to act as a fluidic core waveguide.

Fig. 16A and 16B depict two schematic diagrams of a waveguide structure 1600 including a doped oxide substrate 1608 and a capping layer 1660 below the bonded cladding layer 1620, according to some embodiments. Fig. 16A shows a cross-sectional view from two angles of the waveguide structure 1600, where the two views are divided by a dashed line indicating a 90 ° angle 1602. Fig. 16B shows a top view of the waveguide structure 1600.

The waveguide structure 1600 shown in fig. 16 may share any one or more characteristics in common with the waveguide structure 1500 shown in fig. 15 and may differ from the structure 1500 shown in fig. 15 in that: the structure 1600 may additionally include a protective layer 1660 atop the monolithic oxide substrate 1608 and below the capping layer 1620, which protective layer 1660 may optically protect waveguides (e.g., solid core waveguide 1614, fluid core waveguide 1618) formed in the monolithic oxide substrate 1608. A protective layer 1660 may be disposed (e.g., deposited or placed) on the oxide substrate 1608 after the doping of the oxide substrate 1608 is performed. In some embodiments, the protective layer 1660 may include one or more oxides. The etch can then be into the protective layer 1660 and the oxide substrate 1608 and/or through the protective layer 1660 and the oxide substrate 1608 simultaneously.

In some embodiments of fig. 16 and/or other waveguide structures discussed herein, the doped oxide (e.g., layer 1608) can have a refractive index less than or equal to 1, 2, 3, or 4. In some embodiments of fig. 16 and/or other waveguide structures discussed herein, the doped oxide (e.g., layer 1608) can have a refractive index greater than or equal to 1, 2, 3, or 4.

Fig. 17A and 17B depict two schematic views of a waveguide structure 1700 formed by oxidizing and doping a machined substrate layer 1708 to form a waveguide layer XXX, according to some embodiments. Fig. 17A shows a cross-sectional view from two angles of a waveguide structure 1700, where the two views are divided by a dashed line indicating a 90 ° angle 1702. Fig. 17B shows a top view of the waveguide structure.

The waveguide structure 1700 shown in fig. 17 may share any one or more characteristics in common with the waveguide structure 100 shown in fig. 1. Unlike some other embodiments discussed herein, the technique shown in fig. 17 may depend largely on machining one or more features into the silicon substrate 1708 (or other non-oxide substrate) in addition to or instead of etching into one or more oxides. In some embodiments, waveguide structure fabrication techniques that rely on machining into silicon or other substrate material 1708 may be simpler, faster, more efficient, and less expensive than techniques that rely primarily or exclusively on etching into oxide, because machining silicon may be a simpler and more standardized process than etching into oxide.

In some embodiments, a trench corresponding to the fluid channel 1718 can be machined (e.g., micromachined) from the substrate 1708, and a trench corresponding to the air gap 1716 surrounding the fluid channel 1718 and the intersecting solid core waveguide 1714 can be machined (e.g., micromachined) from the substrate 1708. Thus, the geometry of the fluid channels 118 and air gaps 116 etched into the oxide 106, 110 as shown in fig. 1 may be replicated, except that the geometry may be formed in the substrate 1708 (e.g., a silicon wafer) instead of in the waveguide layer 104, such as oxide.

After forming the geometry in the substrate 1708 via machining, a portion 1762 of the machined substrate 1708 (e.g., a portion near a top surface and/or near a surface exposed to the machined trenches, channels, or gaps) may then be converted (e.g., transformed) to a waveguide material to form an oxide 1706 (e.g., silicon dioxide) for the waveguide layer 1704 from the portion 1762 of the substrate layer 1708. In some implementations, the portion 1762 of the machined substrate 1708 can be converted via oxidation (e.g., thermal oxidation) to convert silicon to silicon dioxide and thereby form silicon dioxide 1706 for the waveguide layer 1704 in the portion 1762 of the previously machined silicon substrate 1708. Silicon dioxide 1706 formed from the substrate may mimic the geometry of the machined substrate 1708. Thus, the silicon dioxide material 1706 used to form the waveguide layer 1704 may be formed from the machined substrate layer 1708 to include fluid channels 1718 and air gaps 1716 formed from respective machined trenches in the substrate layer 1708.

After forming the silicon dioxide material 1706 for the waveguide layer 1704 (e.g., by oxidizing the portion 1762 of the silicon substrate 1708 to form the silicon dioxide waveguide layer 1704), the waveguide layer 1704 may be doped with ions (e.g., see discussion of ion doping above) near a surface (e.g., top surface 1758) of the waveguide layer 1704 to create one or more regions of high index oxide 1710 near the doped surface (e.g., top surface 1758) and thereby complete formation of the waveguide layer 1704. In this manner, the refractive index near the doped surface (e.g., top surface 1758) may be higher than the refractive index away from the doped surface (e.g., top surface 1758). In some embodiments, the entire surface of the waveguide layer 1704 may be subjected to blanket doping, and thus, the doping features 1710 defined in the waveguide layer 1704 by its formation from the machined substrate 1708 may define the solid core waveguide 1714 and/or the waveguide fluidic channel 1718. In some embodiments, the solid core waveguide 1714 is formed as shown by a doped ledge of oxide 1706 located to the left of the 90 degree angle 1702. In some embodiments, a waveguide fluid channel 1718 is formed as shown by the space between two doped protruding channel wall oxide portions 1766 located to the right of the 90 degree angle 1702. Due to the higher refractive index, the excitation light 1712 in the fluid core waveguide 1718 defined between the doped wall portions 1766 located between the air gaps 1716 may be prevented from leaking out and/or down.

In some embodiments, the doping of the oxide layer 1706 may be used to create a graded index of refraction in all or a portion of the oxide layer 1706, while in some embodiments the index of refraction may vary in one or more spatial step functions according to one or more spatial profiles and/or according to one or more spatial gradients.

In some embodiments, a protective layer (not shown in fig. 17A, but which may include one or more oxides in some embodiments) may be disposed (e.g., deposited or placed) on the oxide layer 1706 after the doping of the layer 1706 is performed.

Finally, a cover layer 1720 may be added to enclose the fluid channel 1718. Overlay 1720 may share any one or more features with other overlays (e.g., overlay 120) discussed elsewhere herein.

Fig. 18A and 18B depict two schematic views of a waveguide structure 1800 formed by oxidizing and doping a machined substrate layer 1801 to form a waveguide layer 1804, according to some embodiments. Fig. 18A shows cross-sectional views from two angles of the waveguide structure 1800, where the two views are divided by a dashed line indicating a 90 ° angle 1802. Fig. 18B shows a top view of the waveguide structure 1800.

The waveguide structure 1800 shown in fig. 18 may share any one or more characteristics in common with the waveguide structure 1700 shown in fig. 17, and may differ from the waveguide structure 1700 discussed above with respect to fig. 17 in that: after doping the oxide 1806 in the silicon dioxide portion of the waveguide layer 1804 to create one or more oxide regions 1810 having a higher index of refraction, and before adding the cladding layer 1820, a second oxide layer 1868 may be disposed (e.g., deposited or placed) atop the doped high index oxide layer 1810. Second oxide layer 1868 may be deposited, for example, by conformal coating. In some embodiments, the second oxide layer 1868 may have a lower index of refraction than the doped portion 1810 of the first oxide layer 1806. In some embodiments, the addition of second oxide layer 1868 may protect the waveguide properties of first oxide layer 1806.

After depositing the second oxide layer 1868, a capping layer 1820 may then be added to close the fluid channel 1818. The capping layer 1820 may be bonded or attached directly to the uppermost oxide layer (e.g., layer 1868), and may share any one or more properties with other capping layers discussed elsewhere herein (e.g., capping layer 1720).

Fig. 19 depicts two schematic diagrams of a waveguide structure 1900 including an air gap 1916 formed in a substrate layer 1908 and including lenses 1938 and 1940 for light collection and including an aperture layer 1970, according to some embodiments. Fig. 19A shows cross-sectional views from two angles of a waveguide structure 1900, where the two views are divided by a dashed line indicating a 90 ° angle 1902. Fig. 19B shows a top view of the waveguide structure.

The waveguide structure 1900 shown in fig. 19 may share any one or more characteristics in common with the waveguide structure 1100 shown in fig. 11 and may differ from the waveguide structure 1100 discussed above with respect to fig. 11 in that: the structure 1900 may also include an aperture layer 1970, the aperture layer 1970 configured to allow light from the signal to pass through the aperture 1972 for collection while blocking other light. In some implementations, one or more holes formed in the aperture layer 1970 may be positioned near the fluid channel 1918 and near the lens 1940 embedded in the substrate layer 1908 to allow signal light to pass from the fluid channel 1918 through the aperture layer 1970 and into the lens 1940 in the substrate 1908 for collection while blocking background light that does not pass through the holes 1972 but is blocked by opaque portions of the aperture layer 1970.

In some embodiments, the aperture layer 1970 may include one or more adjacent apertures, apertures of different shapes, a plurality of apertures forming one or more patterns, and/or spectrally-related apertures (e.g., in some embodiments, the aperture layer 1970 may include a stack of ARROW layers). In some embodiments, one or more holes in the aperture layer 1970 may be used to spatially filter the excitation light such that, for example, an excitation light beam incident on the waveguide structure 1900 may only be able to pass through the one or more holes in the aperture layer 1970.

As shown in fig. 19, an aperture layer 1970 may be positioned above substrate layer 1908 (e.g., a silicon layer) and lens 1940 embedded in substrate layer 1908, and may be positioned below fluid channel 1918 and adjacent to fluid channel 1918. In some implementations, as shown in the example of fig. 19, the aperture layer 1970 can be embedded in a portion of the waveguide layer 1904, for example, by sandwiching the aperture layer 1970 between two different low-index oxide layers. In some embodiments, as shown in fig. 19, a three-layer sandwich comprising two low refractive index oxide layers surrounding an aperture layer 1970 may itself be sandwiched between a substrate layer and a high refractive index oxide layer.

An additional difference between fig. 19 and fig. 11 is that: waveguide layer 1904 of fig. 19 includes both a low index of refraction oxide layer (e.g., layer 1906) and a high index of refraction oxide layer (e.g., layer 1910). In some embodiments, positioning the aperture layer 1970 between two low-index oxide layers (and/or suspending the aperture layer in the center of a single low-index oxide layer 1906) may optically isolate the aperture layer 1970 from the waveguide in the waveguide layer 1904, thereby preventing the aperture layer 1970 from absorbing light from the waveguide. Further, positioning the aperture layer 1970 between two low-index oxide layers (and/or suspending the aperture layer in the center of a single low-index oxide layer 1906) may physically isolate the aperture layer 1970 from the substrate layer 1908 and/or from an upper portion of the waveguide layer (e.g., layer 1910), thereby allowing etching and other post-processing steps to be performed on the substrate layer 1908 and/or an upper portion of the waveguide layer (e.g., layer 1910) without damaging or damaging the aperture layer 1970.

In some implementations, the aperture layer 1970 can include chromium, nickel, another metal, one or more ARROW layers (e.g., patterned ARROW layers), and/or another opaque material configured to block background light. In some embodiments, the aperture layer 1970 may be microfabricated such that one or more features of the aperture itself may be formed using microfabrication (e.g., including sputtering, e-beam evaporation, spin coating, and/or one or more coating techniques). In some embodiments, the substrate layer 1908 (e.g., a silicon substrate layer) may be coated with a thick layer (e.g., about equal to or greater than or equal to 2 μm) of optically transparent material that forms the lowermost low refractive index oxide layer 1906 (in some embodiments, this lowermost low refractive index oxide layer 1906 may have the same or similar dimensions as the other lowermost low refractive index oxide layers discussed herein). Micro-fabrication may then be used to create one or more features (e.g., one or more holes) in a thin (e.g., approximately equal to or less than 0.1 μm) layer of patterned absorber material to form an aperture layer 1970 (in some embodiments, the aperture layer 1970 may have the same or similar dimensions as the other aperture layers discussed herein). Next, a thick layer of optically clear low refractive index material (e.g., approximately equal to or greater than 1 μm, 5 μm, or 10 μm) may be deposited on top of the aperture layer to form another low refractive index oxide layer of the isolating aperture layer (where, in some embodiments, the low refractive index oxide layer of the isolating aperture layer may have the same or similar dimensions as the other lowermost or substrate-adjacent low refractive index oxide layer discussed herein). A higher index of refraction material may then be deposited atop the low index oxide layer to form the high index of refraction regions of the waveguide layer (where the high index of refraction regions may have the same or similar thickness as the other high index of refraction oxide layers discussed herein). A single lithographic process, which may be aligned with features of the absorber layer (e.g., aligned to form a fluidic channel over a hole in the aperture layer 1970), may then be used to simultaneously define the fluid core waveguide 1918 and the solid core waveguide 1914 in the waveguide layer 1904.

In some embodiments, the substrate 1908 of the waveguide structure 1900 of fig. 19 can include a low-index material, such as a low-index oxide. In some implementations, an aperture layer 1970 that shares one or more properties in common with the aperture layer described with respect to fig. 19 may be incorporated into any one or more of the other non-axial detection waveguide structures described herein.

Although the disclosure herein has discussed the use of certain oxide materials in the waveguide layers of a waveguide structure, however, in some embodiments, the waveguide layer of the structures disclosed herein may be formed (in whole or in part) from one or more alternative or additional materials, including but not limited to materials deposited using vapor deposition (e.g., oxides deposited via Plasma Enhanced Chemical Vapor Deposition (PECVD) or Low Pressure Chemical Vapor Deposition (LPCVD), such as titanium dioxide), materials formed via thermal oxidation (e.g., silicon dioxide formed by thermal oxidation of silicon), spin-on glass, any one or more other materials that may be selected or configured for background reduction, and/or one or more plastics (e.g., Polydimethylsiloxane (PDMS), Cyclic Olefin Copolymer (COC), Cyclic Olefin Polymer (COP)).

In some embodiments, after fabrication of the waveguide structure according to any one or more of the fabrication techniques disclosed herein, one or more additional processes may be performed to further modify the fabricated chip, including but not limited to deposition, chemical modification, surface chemical changes, and/or topological changes. In some embodiments, these one or more additional processes may be used to modify and/or enhance one or more properties of the manufactured structure, such as hydrophobicity, smoothness, and/or reactivity of the manufactured structure.

The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the technology and its practical applications. To thereby enable others skilled in the art to best utilize the technology and various embodiments with various modifications as are suited to the particular use contemplated.

While the present disclosure and examples have been fully described with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the present disclosure and examples as defined by the following claims. Finally, the entire disclosure of any and all patents and publications mentioned in this application are hereby incorporated by reference herein.