阅读说明：本技术 一种偏振器件及其制备方法 (Polarizing device and preparation method thereof ) 是由 欧欣 王成立 于 2020-07-03 设计创作，主要内容包括：本发明涉及集成光学技术领域,特别涉及一种偏振器件及其制备方法。包括：支撑层和模式筛选层,所述支撑层用于支撑所述所述模式筛选层；所述模式筛选层包括光吸收层和光隔离层,所述光吸收层设置在所述支撑层上,所述光隔离层设置在所述光吸收层上；所述光吸收层用于吸收预设光波导模式的光。光吸收层可以选择性吸收TM模式以及其他高阶模式的光波,光隔离层可以限制光吸收层对光波能量的吸收程度。本申请所述的偏振器件对光偏振的控制,是基于整个电路衬底进行改进来实现的,当光学结构大规模的在片上集成时,模式筛选层可对所有的光学结构中的光波进行偏振筛选,因此无须在光路上重复制备大量偏振控制结构,降低了工艺难度。(The invention relates to the technical field of integrated optics, in particular to a polarizing device and a preparation method thereof. The method comprises the following steps: the supporting layer is used for supporting the mode screening layer; the mode screening layer comprises a light absorption layer and a light isolation layer, the light absorption layer is arranged on the supporting layer, and the light isolation layer is arranged on the light absorption layer; the light absorption layer is used for absorbing light of a preset optical waveguide mode. The light absorption layer can selectively absorb light waves in a TM mode and other high-order modes, and the light isolation layer can limit the absorption degree of the light absorption layer to the light wave energy. The control of polarization of light of polarization device described in this application improves and realizes based on whole circuit substrate, when the large-scale integration on the piece of optical structure, the mode screening layer can carry out the polarization screening to the light wave in all optical structures, consequently need not prepare a large amount of polarization control structures repeatedly on the light path, has reduced the technology degree of difficulty.)

1. A polarizing device, comprising: a support layer (101) and a pattern screening layer,

the supporting layer (101) is used for supporting the mode screening layer;

the mode screening layer comprises a light absorption layer and a light isolation layer (103), the light absorption layer is arranged on the support layer (101), and the light isolation layer (103) is arranged on the light absorption layer;

the light absorption layer is used for absorbing light of a preset optical waveguide mode.

2. The polarizing device of claim 1, wherein the light absorbing layer is a metallic light absorbing layer (102).

3. The polarizing device of claim 2, wherein the material of the metallic light absorbing layer (102) comprises at least one of gold, titanium, copper, platinum, nickel, and chromium.

4. The polarizing device of claim 3, wherein the metallic light absorbing layer (102) has a thickness of 2nm to 50 nm.

5. The polarizing device according to claim 1, further comprising an optical waveguide medium layer disposed on the optical isolation layer (103), the optical waveguide medium layer having at least one optical waveguide structure (104) disposed therein.

6. The polarizing device of claim 5, wherein the light isolating layer (103) has a refractive index less than the optical waveguide medium layer.

7. The polarizer device of claim 6, wherein the material of the optical waveguide medium layer comprises lithium niobate, quartz, silicon dioxide, diamond, silicon carbide, and silicon nitride.

8. The polarization device of claim 7, wherein the optical waveguide structure (104) comprises at least one of a rectangular waveguide structure, a ridge waveguide structure, a trapezoidal waveguide structure, and an arc waveguide structure.

9. The polarization device of claim 1 or 8, wherein the material of the light isolation layer (103) comprises at least one of silicon dioxide, titanium dioxide, air cavity, glass medium; and/or the presence of a gas in the gas,

the thickness of the light isolation layer (103) is 50nm-5 μm.

10. A method of making a polarizing device, comprising:

manufacturing a metal light absorption layer (102) on the support layer (101);

manufacturing a light isolation layer (103) on the metal light absorption layer (102);

manufacturing an optical waveguide medium layer on the optical isolation layer (103);

and manufacturing an optical waveguide structure (104) in the optical waveguide medium layer.

Technical Field

The invention relates to the technical field of integrated optics, in particular to a polarizing device and a preparation method thereof.

Background

The development of information technology is always pursuing greater integration and faster information processing speed. In recent years, due to physical principles, microelectronics have been difficult to improve the size and performance of basic element transistors. To continue to increase the information processing speed, it is conceivable to use another information carrier, photons. Compared with electrons, photons have more stable and controllable modulation and multiplexing dimensions such as amplitude, phase, wavelength, polarization state, mode and the like, and have larger bandwidth, higher spectrum utilization rate and higher communication capacity. The integrated photonics technology shows great application value in various fields such as data centers, communication, sensing and the like due to the advantages of high integration level, small size, compatibility with microelectronic processes and the like.

The field of integrated optics utilizes optical waveguides to transmit light waves. Optical waves are confined in optical waveguide structures that typically have different polarization modes, such as a quasi-transverse electric mode (TE mode) and a quasi-transverse magnetic mode (TM mode). Since some optical information processing elements such as electro-optical modulators, etc. only support the TE mode, and the TM mode generally has higher bending loss, the transmission loss increases if the polarization state of light changes during waveguide transmission. One of the key technologies for transmitting information by using photons is to ensure that the polarization state of photons in the optical path is stable. To solve this problem, a light polarization control device on a multi-pass sheet has been proposed. Such as: the TM mode is scattered through the cascaded bent waveguide, and the TE mode is reserved to realize polarization control; the TM mode is selectively coupled to the other waveguide branch by using an asymmetric directional coupler to realize polarization control; there are also techniques for selectively removing TM modes using meta-materials placed on both sides of the waveguide, etc. The above methods all implement polarization control of local propagation regions through local structures, and when the optical structures are integrated on a large scale on a chip, the above methods require repeated preparation of a large number of structures on the optical path to implement polarization control, which poses a challenge to process stability.

Disclosure of Invention

The invention aims to solve the technical problem that the process difficulty is high because a large number of polarization structures are required to be repeatedly prepared to realize polarization control when the conventional light polarization device is applied to a large-scale integrated optical circuit.

In order to solve the above technical problem, in a first aspect, an embodiment of the present application discloses a polarization device, including: a support layer and a mode screening layer,

the supporting layer is used for supporting the mode screening layer;

the mode screening layer comprises a light absorption layer and a light isolation layer, the light absorption layer is arranged on the supporting layer, and the light isolation layer is arranged on the light absorption layer;

the light absorption layer is used for absorbing light of a preset optical waveguide mode.

Further, the light absorption layer is a metal light absorption layer.

Further, the material of the metal light absorption layer includes at least one of gold, titanium, copper, platinum, nickel, and chromium.

Further, the thickness of the metal light absorption layer is 2nm-50 nm.

Furthermore, the polarization device further comprises an optical waveguide medium layer, the optical waveguide medium layer is arranged on the optical isolation layer, and at least one optical waveguide structure is arranged in the optical waveguide medium layer.

Further, the refractive index of the optical isolation layer is smaller than that of the optical waveguide medium layer.

Furthermore, the material of the optical waveguide medium layer comprises lithium niobate, quartz, silicon dioxide, diamond, silicon carbide and silicon nitride.

Further, the optical waveguide structure comprises at least one of a rectangular waveguide structure, a ridge waveguide structure, a trapezoidal waveguide structure and an arc waveguide structure.

Further, the material of the light isolation layer comprises at least one of silicon dioxide, titanium dioxide, an air cavity and a glass medium; and/or the presence of a gas in the gas,

the thickness of the light isolation layer is 50nm-5 μm.

In a second aspect, an embodiment of the present application discloses a method for manufacturing a polarizer, including:

manufacturing a metal light absorption layer on the supporting layer;

manufacturing a light isolation layer on the metal light absorption layer;

manufacturing an optical waveguide medium layer on the optical isolation layer;

and manufacturing an optical waveguide structure in the optical waveguide medium layer.

By adopting the technical scheme, the polarizing device and the preparation method thereof have the following beneficial effects:

the polarization device of the embodiment of the application directly sets up the light absorption layer and the light isolation layer on the supporting layer, the light absorption layer can selectively absorb light waves in a TM mode and other high-order modes, and the light isolation layer can limit the absorption degree of the light absorption layer to light wave energy, so that the polarization state of photons in a light path is ensured to be stable. The control of polarization of light of polarization device described in this application improves and realizes based on whole circuit substrate, when the large-scale integration on the piece of optical structure, the mode screening layer can carry out the polarization screening to the light wave in all optical structures, consequently need not prepare a large amount of polarization control structures repeatedly on the light path, has reduced the technology degree of difficulty.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic view of a polarizer device according to an embodiment of the present application;

FIG. 2 shows the propagation distance of each polarization mode for different thicknesses of the light-isolating layer according to an embodiment of the present application;

FIG. 3 is a schematic diagram of the mode field distribution of the TE0 mode according to one embodiment of the present application;

FIG. 4 is a schematic diagram of the mode field distribution of the TM0 mode in accordance with one embodiment of the present application;

FIG. 5 is a schematic diagram of the mode field distribution of the TE1 mode according to one embodiment of the present application;

FIG. 6 is a schematic diagram of the mode field distribution of the TM1 mode in accordance with one embodiment of the present application;

the following is a supplementary description of the drawings:

101-a support layer; 102-a metallic light absorbing layer; 103-a light isolating layer; 104-optical waveguide structure.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic may be included in at least one implementation of the present application. In the description of the present application, it is to be understood that the terms "upper", "lower", "top", "bottom", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Moreover, the terms "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein.

In order to ensure that the polarization state of photons in the optical path remains stable, various optical polarization control devices on the chip have been proposed. However, the existing polarization control devices implement polarization control of a local propagation region through a local structure, and when an optical structure is integrated on a chip in a large scale, a large number of structures need to be repeatedly prepared on an optical path to implement polarization control, so that the process implementation difficulty is high, and the cost is high.

The embodiment of the application discloses a polarization device, includes: the device comprises a supporting layer 101 and a mode screening layer, wherein the supporting layer 101 is used for supporting the mode screening layer; the mode screening layer includes a light absorbing layer disposed on the support layer 101 and a light isolating layer 103 disposed on the light absorbing layer; the light absorption layer is used for absorbing the light of the preset light waveguide mode.

In the polarization device according to the embodiment of the present application, the light absorption layer and the optical isolation layer 103 are directly disposed on the support layer 101, the light absorption layer can selectively absorb light waves in TM mode and other high-order modes, and the optical isolation layer 103 can limit the absorption degree of the light absorption layer on light wave energy, so as to ensure that the polarization state of photons in the light path remains stable. The control of polarization of light of polarization device described in this application improves and realizes based on whole circuit substrate, when the large-scale integration on the piece of optical structure, the mode screening layer can carry out the polarization screening to the light wave in all optical structures, consequently need not prepare a large amount of polarization control structures repeatedly on the light path, has reduced the technology degree of difficulty.

In the embodiment of the present application, the supporting layer 101 is used to support a polarizer structure, optionally, the supporting layer 101 is an independent supporting substrate, and in an integrated optical circuit, the supporting layer 101 is a substrate of an optical path structure. Optionally, the support layer 101 is a common wafer substrate such as a silicon substrate, a silicon-on-insulator substrate, or the like. A light absorbing layer is disposed on the substrate layer, the light absorbing layer capable of absorbing light in the transverse magnetic mode and other higher order modes in the optical waveguide structure 104. The light absorption layer is formed by depositing materials with larger refractive index, such as metal, metal oxide and the like. The light isolation layer 103 is disposed on the surface of the light absorption layer to prevent the light absorption layer from excessively absorbing light in the light guide structure 104, which results in excessive light loss and is not favorable for light wave transmission.

The light absorbing layer is a metallic light absorbing layer 102.

In the embodiment of the present application, the optical wave is an electromagnetic wave, and is attenuated by heat loss when propagating in the metal, so that the metal medium absorbs the light. The light wave in an absorption medium is a monochromatic plane wave, the most important optical properties of a metal are its absorption and reflection of light, and both the reflectivity and the absorptivity are their complex refractive indices: n ═ n-i χ; where n is the real refractive index and χ is the extinction coefficient, determines the attenuation of the wave. The light absorbing layer is preferably a metal layer because of its large extinction coefficient in refractive index.

The material of the metal light absorption layer 102 includes at least one of gold, titanium, copper, platinum, nickel, and chromium.

In the embodiment of the present application, the material of the light absorption layer may be made of a metal with a good light wave absorption effect, so as to ensure that the metal light absorption layer 102 can effectively absorb the light waves of the transverse magnetic mode and other high-order modes thereof, thereby achieving a stable polarization effect. Alternatively, the metal light absorption layer 102 may be a single metal layer or may include multiple metal layers. The metal layer can be made of a single metal or a composite or alloy of multiple metals.

The thickness of the metal light absorption layer 102 is 2nm to 50 nm.

In the embodiment of the present invention, the metal light absorption layer 102 has the function of absorbing the transverse magnetic mode and other high-order modes of the transverse magnetic mode, and the thickness of the metal light absorption layer 102 is determined by the material of the metal, the refractive index of the metal, and other factors.

The polarization device further comprises an optical waveguide medium layer, the optical waveguide medium layer is arranged on the optical isolation layer 103, and at least one optical waveguide structure 104 is arranged in the optical waveguide medium layer.

In the present embodiment, the optical waveguide medium layer is formed by one or more optical waveguide structures 104, and the optical waveguide structures 104 are used for guiding light waves to propagate therein. An optical isolation layer 103 is arranged between the optical waveguide structure 104 and the metal light absorption layer 102, the optical wave propagates in the optical waveguide structure 104, the metal light absorption layer 102 absorbs the transverse magnetic mode and other optical waves of high-order modes in the optical wave, and only the transverse electric mode is left to propagate in the optical waveguide structure 104, so that stable control of polarization is realized. In practical applications, the mode screening layer may be disposed on any surface of the optical waveguide structure 104.

The refractive index of the light-isolating layer 103 is less than that of the optical waveguide medium layer.

In the embodiment of the present application, in order to ensure the propagation of the light wave in the optical waveguide structure 104, the refractive index of the optical isolation layer 103 must be smaller than that of the optical waveguide medium layer.

The material of the optical waveguide medium layer comprises lithium niobate, quartz, silicon dioxide, diamond, silicon carbide and silicon nitride.

In the embodiment of the present application, the material of the optical waveguide medium layer is selected according to the optical waveguide mode and the type of the optical waveguide structure 104.

The optical waveguide structure 104 includes at least one of a rectangular waveguide structure, a ridge waveguide structure, a trapezoidal waveguide structure, and an arc waveguide structure.

In the embodiment of the present application, the optical waveguide structure 104 may be a planar waveguide structure or a three-dimensional waveguide structure. In some embodiments, a plurality of optical waveguide structures 104 are disposed in the optical waveguide medium layer, and the types of the plurality of optical waveguide structures 104 may be the same or different. Since the metal light absorption layer 102 is used for absorbing the transverse magnetic mode, so that the transverse electric mode is retained in the optical waveguide structure 104, the optical wave needs to have both the transverse magnetic mode and the transverse electric mode in the optical waveguide structure 104.

The material of the light isolation layer 103 comprises at least one of silicon dioxide, titanium dioxide, an air cavity and a glass medium; and/or the light isolation layer 103 has a thickness of 50nm to 5 μm.

In the embodiment of the present application, the light isolation layer 103 is made of a common light guide material, and the specific material can be selected according to the material and structure of the light guide and the use cost. Since the thickness of the light isolation layer 103 affects the absorption degree of the light waves, if the thickness of the light isolation layer 103 is too thin, the metal light absorption layer 102 will absorb all the light waves in the optical waveguide structure 104; if the thickness of the optical isolation layer 103 is too thick, the metal light absorption layer 102 cannot absorb the transverse magnetic mode and other high-order mode light waves in the optical waveguide structure 104, and cannot perform a polarization filtering function, so the thickness of the optical isolation layer 103 should be selected to be a suitable thickness according to the material of the optical isolation layer 103, and optionally, the thickness of the optical isolation layer 103 is 50nm-5 μm. As shown in fig. 2, the effect of the thickness of the light-isolating layer 103 on the polarization-controlling performance is shown in fig. 2. By changing the thickness of the light-isolating layer 103, the propagation lengths of the modes in the waveguide are calculated separately, curve 1 being the TE0 mode, curve 2 being the TE1 mode, curve 3 being the TM0 mode, and curve 4 being the TM1 mode. Taking the example that the material of the light isolation layer 103 is silicon dioxide, when the thickness of the light isolation layer 103 is less than 300nm, the propagation length of each mode is very small, because the optical power of each mode is absorbed by a large amount of metal. When the thickness of the optical isolation layer 103 is greater than 700nm, the propagation length of the TE0 mode is 1000 times that of the other modes, about 30dB, so by adjusting the thickness of the optical isolation layer 103, the on-chip polarization selection ratio can be made to be 30 dB. It should be noted that the thickness of the light isolation layer 103 cannot be too large, otherwise the TM0, TE1, TM1 modes cannot be effectively removed.

The embodiment of the application also discloses a preparation method of the polarizing device, which comprises the following steps: manufacturing a metal light absorption layer 102 on the support layer 101; forming a light isolation layer 103 on the metal light absorption layer 102; manufacturing an optical waveguide medium layer on the optical isolation layer 103; an optical waveguide structure 104 is fabricated in the optical waveguide dielectric layer.

In the embodiment of the present application, the supporting layer 101 may be a common wafer substrate such as a silicon substrate, a silicon-on-insulator, and the like, and the metal light absorption layer 102 is fabricated on the supporting layer 101, and optionally, the metal light absorption layer 102 is made of gold, titanium, copper, platinum, and the like; optionally, the manufacturing method of the metal light absorption layer 102 includes electron beam evaporation, magnetron sputtering, molecular beam epitaxy, and the like. After the metal light absorption layer 102 is manufactured, the light isolation layer 103 is manufactured on the metal light absorption layer 102, optionally, the material of the light isolation layer 103 is silicon dioxide, titanium dioxide, an air cavity, a glass medium, and the like, and the thickness of the light isolation layer 103 is 50nm-5 μm. After the light isolation layer 103 is manufactured, an optical waveguide medium layer is deposited on the light isolation layer 103, and then an optical waveguide structure 104 is manufactured in the optical waveguide medium layer, wherein optionally, the optical waveguide structure 104 includes a rectangular waveguide structure, a ridge waveguide structure, a trapezoidal waveguide structure, and an arc waveguide structure. The preparation method provided by the embodiment of the application provides a polarization control mode for a large-scale integrated optical circuit, and the metal light absorption layer 102 is arranged under the waveguide structure to selectively absorb transverse magnetic modes and other high-order modes of light waves. The above-mentioned improvement of the polarization implementation method is not limited to the area structure, but the whole circuit substrate is improved, so that the polarization device structure described in the present application can be applied to the whole polarization control in the large-scale integrated optical circuit.

In the embodiment of the application, the polarization control effect of the polarization device in the embodiment of the application is verified by designing the structural parameters of the polarization device. Fig. 3 to 6 show mode field distributions of the TE0 and TM0 fundamental modes supported in the optical waveguide structure 104 and their corresponding higher-order modes TE1 and TM1, respectively, through the optical waveguide structure 104. In fig. 3 to 6, the rectangular frame is the optical waveguide structure 104, and the light wave outside the area of the optical waveguide structure 104 is absorbed by the light absorption layer. As can be seen from the mode field distributions of fig. 3 to 6, only the mode field of the TE0 mode is tightly bound in the optical waveguide medium layer with a rectangular structure, and the mode distributions of TM0, TE1 and TM1 are all absorbed by the metal light absorption layer 102 in the structure. The loss condition of each mode is accurately calculated by a numerical calculation method.

Calculating the TE0 mode in fig. 3, the effective index of the optical waveguide structure 104 is 1.615, and the imaginary part is infinitesimally small, indicating that its propagation loss is negligible, calculating the TM0 mode in fig. 4, the effective index of the optical waveguide structure 104 is 1.5-6 × 10-4i, and it is known that its imaginary part k is-6 × 10^-4According to the formula:

wherein λ is a target wavelength; the absorption coefficient α is converted to the absorption coefficient α, which is converted to the propagation length 1/α, where e is 2.7182 microns, and the power loss 1/e is converted to the propagation length. The same calculation calculates the TE1 higher order mode in FIG. 5, with an effective index of refraction of 1.6-1.5X 10-5i and a propagation length of 672 microns. Calculating the TM1 higher order mode in fig. 6, the effective refractive index is 1.5-1.9 x 10-3i, and the propagation length is 5.3 microns. Comparing these modes, it can be seen that under the action of the metal light absorption layer 102, the TM0, TE1, TM1, etc. modes are attenuated within a specific propagation length, while the TE0 mode is left, so as to realize the polarization control function.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.