阅读说明：本技术 一种硅光光模斑模式转换器及其制造方法 (Silicon optical mode spot mode converter and manufacturing method thereof ) 是由 朱云鹏 田斌 黄小伟 夏晓亮 于 2019-11-19 设计创作，主要内容包括：本发明提供一种硅光光模斑模式转换器及其制造方法,包括二氧化硅悬臂、过渡波导、主波导、硅衬底、第一包层、第二包层、第三包层,所述第一包层置于所述硅衬底上方,所述主波导置于第一包层上方,所述主波导与过渡波导中间为第二包层,所述过渡波导上设置第三包层；所述二氧化硅悬臂接于过渡波导外侧,所述二氧化硅悬臂光路中心与所述过渡波导光路中心在同一纵向截面；所述二氧化硅悬臂宽度和厚度沿输入光路方向逐渐减小。可以解决硅基光电子芯片与光纤或激光器的光模斑不匹配,导致的耦合效率低的问题,能有效提高硅光芯片与外界光源/光纤的耦合效率。(The invention provides a silicon optical mode spot mode converter and a manufacturing method thereof, and the silicon optical mode spot mode converter comprises a silicon dioxide cantilever, a transition waveguide, a main waveguide, a silicon substrate, a first cladding, a second cladding and a third cladding, wherein the first cladding is arranged above the silicon substrate, the main waveguide is arranged above the first cladding, the second cladding is arranged between the main waveguide and the transition waveguide, and the third cladding is arranged on the transition waveguide; the silica cantilever is connected to the outer side of the transition waveguide, and the center of the optical path of the silica cantilever and the center of the optical path of the transition waveguide are on the same longitudinal section; the width and thickness of the silicon dioxide cantilever are gradually reduced along the direction of an input optical path. The problem of low coupling efficiency caused by mismatching of the optical mode spots of the silicon-based optoelectronic chip and the optical fiber or the laser can be solved, and the coupling efficiency of the silicon-based optoelectronic chip and an external light source/optical fiber can be effectively improved.)

1. A silicon optical speckle mode converter, comprising: the silicon-based waveguide structure comprises a silicon dioxide cantilever, a transition waveguide, a main waveguide, a silicon substrate, a first cladding, a second cladding and a third cladding, wherein the first cladding is arranged above the silicon substrate, the main waveguide is arranged above the first cladding, the second cladding is arranged between the main waveguide and the transition waveguide, and the third cladding is arranged on the transition waveguide;

the silica cantilever is connected to the outer side of the transition waveguide, and the center of the optical path of the silica cantilever and the center of the optical path of the transition waveguide are on the same longitudinal section;

the width of the silicon dioxide cantilever is gradually reduced along the direction of an input optical path.

2. The silicon optical mode-converter of claim 1, wherein: the silicon dioxide cantilever is provided in a step shape in a width direction thereof.

3. The silicon optical mode-converter of claim 1, wherein: the silicon dioxide cantilever is arranged in a step shape in the height direction thereof.

4. The silicon optical mode-converter of claim 1, wherein: the cross sections of the two ends of the transition waveguide are inverted cones, and the cross section of one end, close to the transition waveguide, of the main waveguide is inverted cone-shaped.

5. The silicon optical mode-converter of claim 4, wherein: the main waveguide is a silicon waveguide, and the refractive index of the transition waveguide ranges from 1.445 to 3.42.

6. The silicon optical mode-converter of claim 5, wherein: the transition waveguide is made of silicon nitride or silicon oxynitride.

7. The silicon optical mode-converter of claim 1, wherein: the silica cantilever is arranged at the front section of the spot-size mode converter, and the first cladding, the second cladding and the third cladding are silica layers.

8. The silicon optical mode-converter of claim 1, wherein: the thickness of the main waveguide is 210 +/-10 nm, the thickness range of the transition waveguide is 400 +/-15 nm, the thickness range of the first cladding layer is 2-4 mu m, the thickness range of the second cladding layer is 80 +/-1 nm, and the thickness range of the third cladding layer is 6.5-8.5 mu m.

9. A method of manufacturing a silicon optical speckle mode converter as claimed in any one of claims 1 to 8, comprising the steps of:

firstly, manufacturing a main waveguide on an SOI (silicon on insulator) by adopting an etching process;

secondly, depositing a silicon dioxide layer on the main waveguide layer to be used as a second cladding, Polishing the surface of the second cladding by using a Chemical-mechanical Polishing mode (Chemical-mechanical Polishing), and simultaneously controlling the thickness of the silicon dioxide cladding on the upper layer of the main waveguide to be 80 +/-1 nm;

thirdly, depositing a transition waveguide layer on the second cladding layer, controlling the thickness of the transition waveguide layer to be 400 +/-15 nm, and then manufacturing a transition waveguide by adopting an etching process;

fourthly, depositing a silicon dioxide layer on the chip after the step is finished to be used as a third cladding, and then polishing the surface of the third cladding in a chemical mechanical polishing mode;

fifthly, after the steps are finished, the step gradual change of the silicon dioxide cantilever waveguide in the longitudinal direction can be realized by using a distributed etching mode;

and sixthly, after the steps are finished, etching through the silicon dioxide cladding layer to the silicon substrate layer by using a dry etching method, and then continuously etching the silicon substrate by using a reactive ion etching mode to realize the cantilever waveguide of the silicon dioxide.

Technical Field

The invention relates to a silicon optical modular spot mode converter and a manufacturing method thereof, in particular to a silicon optical modular spot mode converter realized by utilizing an on-chip integrated micro lens, which is applied to the field of silicon optical subset integration.

Background

With the technological progress in recent years, optical chips with small size and high integration level become the future development trend, and silicon-based optoelectronics can become the mainstream commercial photonic integration platform in the future more and more due to the integration cost and the maturity of the manufacturing process. Conventional photonic integrated platforms with low refractive index difference, such as silicon dioxide and indium phosphide platforms, have a large waveguide section due to the weak confinement of the optical waveguide, and the bending radius of the waveguide is also large (usually in the order of hundreds of micrometers to millimeters), so that it is difficult to integrate a plurality of optical functional devices on a single wafer. Silicon-based opto-electronic technology, which utilizes the SOI (Silicon-on-insulator) wafer process. The platform utilizes the high refractive index of silicon materials to limit the transmission of light waves in the silicon waveguide materials, and not only realizes the nanoscale strong-limit optical waveguide, but also enables the waveguide on the platform to realize an ultra-small bending radius (about 5 mu m) due to the large refractive index difference between the core layer and the cladding layer of the silicon waveguide. However, the size of the silicon waveguide is generally in the submicron level, the diameter of the general single-mode fiber is generally about 8 μm, and how to realize low-loss coupling of the silicon waveguide, an external light source and the fiber slowly becomes a technical difficulty and a key.

To couple the silicon waveguide with the external light source and the optical fiber, two general types of methods are generally used. One method is to use a second-order grating etched on an SOI (silicon on insulator) sheet as a coupling structure, and the method needs to accurately control the angle of coupled light, has limited bandwidth, is sensitive to process requirements and has certain difficulty in large-scale application. Another method is to expand the optical mode in the silicon waveguide using a waveguide structure to enable it to match the laser or fiber mode. However, since the optical mode spot of the silicon waveguide is generally in the submicron order, and the optical mode spot of the optical fiber or laser is generally in the several microns order, a relatively long structure is required for realizing low-loss beam expansion.

Disclosure of Invention

The invention provides a silicon optical mode spot mode converter, which comprises a silicon dioxide cantilever, a transition waveguide, a main waveguide, a silicon substrate, a first cladding, a second cladding and a third cladding, wherein the first cladding is arranged above the silicon substrate, the main waveguide is arranged above the first cladding, the second cladding is arranged between the main waveguide and the transition waveguide, and the third cladding is arranged on the transition waveguide; the silica cantilever is connected to the outer side of the transition waveguide, and the center of the optical path of the silica cantilever and the center of the optical path of the transition waveguide are on the same longitudinal section; the width and thickness of the silicon dioxide cantilever are gradually reduced along the direction of an input optical path. The problem of low coupling efficiency caused by mismatching of the optical mode spots of the silicon-based optoelectronic chip and the optical fiber or the laser can be solved.

The invention designs a silicon dioxide micro-lens structure, integrates an optical mode spot converter into a single chip, can realize the high-efficiency light converging and beam-collecting effect under the high integration level situation, improves the coupling efficiency between a silicon-based optoelectronic chip and an optical fiber or a laser, and reduces the length of a gradual change waveguide in the traditional scheme.

Furthermore, the silicon dioxide cantilever is arranged in a step shape in the width direction, and the high-efficiency light converging and converging effect in the width direction can be realized.

Furthermore, the silica cantilever is arranged in a step shape in the height direction, so that the high-efficiency light converging and converging effect in the height direction can be realized.

Furthermore, the cross sections of the two ends of the transition waveguide are inverted cones, and the cross section of one end, close to the transition waveguide, of the main waveguide is inverted cone, so that high-efficiency optical coupling inside the chip can be realized.

Further, the main waveguide is a silicon waveguide, the refractive index of the transition waveguide ranges from 1.445 to 3.42, the transition waveguide is generally made of silicon nitride, and silicon oxynitride can be selected according to requirements. The transition waveguide has a refractive index between silica and silicon, and is selected to improve the coupling efficiency of light from the silica cantilever into the silicon waveguide due to the tendency of light to couple into the higher index material.

Further, the transition waveguide is made of silicon nitride or silicon oxynitride.

Further, the silica cantilever is arranged at the front section of the spot-size mode converter, and the first cladding, the second cladding and the third cladding are silica layers.

Further, the thickness of the main waveguide is 210 +/-10 nm, the thickness of the transition waveguide is 400 +/-15 nm, the thickness range of the first cladding layer is 2-4 μm, the thickness range of the second cladding layer is 80 +/-1 nm, and the thickness range of the third cladding layer is 6.5-8.5 μm.

The invention also provides a manufacturing method of the silicon optical mode spot mode converter, which comprises the following steps:

firstly, manufacturing a main waveguide on an SOI (silicon on insulator) by adopting an etching process;

secondly, depositing a silicon dioxide layer on the main waveguide layer to be used as a second cladding, Polishing the surface of the second cladding by using a Chemical-mechanical Polishing mode (Chemical-mechanical Polishing), and simultaneously controlling the thickness of the silicon dioxide cladding on the upper layer of the main waveguide to be 80 +/-1 nm;

thirdly, depositing a transition waveguide layer on the second cladding layer, controlling the thickness of the transition waveguide layer to be 400 +/-15 nm, and then manufacturing a transition waveguide by adopting an etching process;

fourthly, depositing a silicon dioxide layer on the chip after the step is finished to be used as a third cladding, and then polishing the surface of the third cladding in a chemical mechanical polishing mode;

fifthly, after the steps are finished, the step gradual change of the silicon dioxide cantilever waveguide in the longitudinal direction can be realized by using a distributed etching mode;

and sixthly, after the steps are finished, etching through the silicon dioxide cladding layer to the silicon substrate layer by using a dry etching method, and then continuously etching the silicon substrate by using a reactive ion etching mode to realize the cantilever waveguide of the silicon dioxide.

Drawings

FIG. 1 is a schematic top view of a cross-sectional view of a silicon optical spot-mode converter in example 1

FIG. 2 is a schematic side view of a silicon optical speckle pattern converter in example 2

FIG. 3 is a schematic side view of a silicon optical mode-converter according to example 3.

Detailed Description

The following provides a more detailed description of the present invention, with reference to the accompanying drawings.