Array Waveguide Grating Layout for Low Loss and Phase Error
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Solution Overview
Problem
Array waveguide gratings face issues of higher insertion loss and larger phase errors due to rough sidewalls and evanescent wave crosstalk in waveguide arrays, which are exacerbated by smaller channel spacing in star couplers.
Innovation Solution
The array waveguide grating employs input and output couplers with higher refractive indices and waveguides with lower refractive indices, manufactured using high-precision photolithography, to confine light fields and reduce crosstalk, while the waveguides use temperature-insensitive materials like silicon nitride or silicon oxynitride to minimize phase errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the channel spacing of the star coupler is reduced to reduce insertion loss, then the insertion loss is reduced, but the evanescent wave crosstalk between adjacent channels significantly increases
Solution Approach 1:
The patent applies different refractive index characteristics to different components: the star coupler uses high refractive index material (first refractive index) to reduce insertion loss, while the waveguides use low refractive index material (second refractive index) to suppress evanescent wave crosstalk. This local differentiation of material properties allows each component to optimize its function independently.
Solution Approach 2:
The invention uses composite material structure with at least two different materials having different refractive indices. The first material (high refractive index) is used for the star coupler, and the second material (low refractive index) is used for the waveguides, creating a composite optical system that achieves both low insertion loss and low crosstalk.
2Device complexity
If waveguide arrays are used, then the structure is simple, but the roughness of the sidewalls causes larger phase errors leading to increased insertion loss and crosstalk
Solution Approach 1:
The patent changes the refractive index parameter of the waveguide material to a lower value (second refractive index less than the first refractive index). This parameter change reduces the sensitivity to sidewall roughness, thereby reducing phase errors even when using relatively simple waveguide array structures.
3Stability of the object's composition
If the refractive index of waveguides is increased to improve light confinement, then the light confinement is improved, but the phase error caused by sidewall roughness increases
Solution Approach 1:
The patent applies different refractive index characteristics to different components: the star coupler uses high refractive index material (first refractive index) to reduce insertion loss, while the waveguides use low refractive index material (second refractive index) to suppress evanescent wave crosstalk. This local differentiation of material properties allows each component to optimize its function independently.
Solution Approach 2:
The invention uses composite material structure with at least two different materials having different refractive indices. The first material (high refractive index) is used for the star coupler, and the second material (low refractive index) is used for the waveguides, creating a composite optical system that achieves both low insertion loss and low crosstalk.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces insertion loss and crosstalk, minimizing spectrum drift and phase errors, thereby improving the efficiency and performance of wavelength division multiplexing systems.
Implementation Method 1
the input coupler has a first refractive index, the plurality of waveguides have a second refractive index, the output coupler has a third refractive index, and both the first refractive index and the third refractive index are greater than the second refractive index
Implementation Method 2
the lower refractive index of the waveguides may reduce the phase error caused by the roughness of the sidewalls of the waveguides
Data Source
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AI summary
The present application relates to an array waveguide grating. The array waveguide grating comprises an input coupler, a waveguide array and an output coupler, wherein the waveguide array is coupled between the input coupler and the output coupler, and the waveguide array comprises a plurality of waveguides; the input coupler is used for allocating received optical signals to the plurality of waveguides, and the waveguides are used for guiding the allocated optical signals; and the output coupler is used for coupling the optical signals, which are transmitted on the plurality of waveguides. The input coupler has a first refractive index, each waveguide has a second refractive index, and the output coupler has a third refractive index, wherein the first refractive index and the third refractive index are both greater than the second refractive index. The array waveguide grating can solve both the problem of an insertion loss of a star coupler being relatively high and the problem of a phase error being relatively large due to the roughness of a side wall of a waveguide, and insertion loss of the array waveguide grating is relatively low.