Asymmetric Waveguide Widths for Phase Error Compensation
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Solution Overview
Problem
Optical hybrids in coherent receivers and LiDAR applications face significant yield reduction due to phase errors, which are difficult to minimize in existing designs.
Innovation Solution
The optical circuit employs waveguides with different input widths to achieve a precise phase difference, allowing for increased fabrication tolerance and accurate phase shifting in 90-degree optical hybrids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical hybrid designs are used, then the device can perform coherent detection functions, but phase errors occur that significantly lower PIC yield
Solution Approach 1:
The patent applies asymmetry by making the waveguides have different input widths instead of identical dimensions. Specifically, at least one of the four waveguides has a different input width than the others, which introduces deliberate asymmetry to compensate for fabrication variations and achieve precise 90-degree phase relationships at the outputs, thereby improving both phase precision and PIC yield
Solution Approach 2:
The patent changes the geometric parameter of the waveguides by varying their input widths. This parameter change allows for compensation of phase errors introduced during fabrication, enabling precise phase control without requiring extremely tight fabrication tolerances, thus improving both phase relationship precision and manufacturing yield
2Manufacturing precision
If fabrication tolerances are tightened to reduce phase errors, then phase precision improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent uses asymmetric waveguide design where at least one waveguide has a different input width than the others. This asymmetry is intentionally designed to compensate for phase errors, allowing the system to achieve high phase precision with relaxed fabrication tolerances, thereby improving ease of manufacture while maintaining manufacturing precision
Solution Approach 2:
The patent modifies the waveguide input width parameter to achieve phase error compensation. By changing this geometric parameter, the system can tolerate wider fabrication variations while still maintaining precise phase relationships, thus improving both manufacturing precision and ease of manufacture
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 configuration enhances the yield of photonic integrated circuits by ensuring precise phase relationships between outputs, improving the accuracy and reliability of coherent receivers and LiDAR systems.
Implementation Method 1
The first waveguide has a first optical connection to the first output and has a propagation length. The second waveguide has a second optical connection to the second output and has the same propagation length as the first waveguide.
Implementation Method 2
The coupler has an input for the signal and has first and second outputs
Data Source
AI summary
An optical circuit for routing a signal includes a coupler and first and second waveguides. The coupler has an input for the signal and has first and second outputs. The first waveguide has a first optical connection to the first output, and the second waveguide has a second optical connection to the second output. Both waveguides have the same propagation length. The first and second waveguides include different widths at the respective optical connections to the respective outputs. This coupler can be used with another input couplers, two additional waveguides, and two 2×2 output couplers to provide a 90-degree hybrid for mixing signal light and local oscillator light in a coherent receiver or the like.