90-Degree Optical Hybrid Arm Waveguide Phase Control
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Solution Overview
Problem
Existing 90-degree optical hybrids face challenges with wavelength dependence in phase difference and increased loss due to tapered waveguides in phase-shift waveguide structures, making them impractical for broad applications.
Innovation Solution
The proposed 90-degree optical hybrid design incorporates two optical splitters, two optical combiners, and four arm waveguides with a bend waveguide and tapered or linear waveguides, where the arm waveguides have a width that decreases towards the bend waveguide, reducing loss and minimizing wavelength dependence by controlling phase differences through arm waveguide configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a phase-shift waveguide with wider width is provided to give a phase difference of 90 degrees to the beams of splitted reference light, then the phase difference is not dependent on wavelength, but the loss increases due to tapered waveguides needed at both ends to suppress scattering loss
Solution Approach 1:
The patent extracts the phase-shifting function from a traditional phase-shift waveguide and implements it through the arm waveguide configuration itself. By setting specific optical path length differences between arm waveguides, the phase difference is achieved without requiring additional phase-shift waveguides with tapered ends, thereby eliminating the associated scattering losses while maintaining wavelength-independent phase stability.
Solution Approach 2:
The patent applies different optical path length characteristics to different arm waveguides locally. Specifically, the fourth arm waveguide is configured with a different optical path length compared to the first, second, and third arm waveguides, creating the necessary phase difference locally at each arm rather than requiring a global phase-shift structure with tapered transitions.
2Volume of stationary object
If an optical splitter is used to split reference light into two beams, then the phase difference given to electric fields becomes dependent on wavelength due to optical path length variation, but the device can be downsized by omitting a phase-shift waveguide
Solution Approach 1:
The patent changes the critical parameter from wavelength-dependent optical path length in splitters to wavelength-independent geometric path length differences in arm waveguides. By controlling the physical lengths and configurations of the arm waveguides rather than relying on splitter characteristics, the system achieves phase stability across wavelengths while maintaining compact dimensions.
Solution Approach 2:
The patent replaces the optical interference-based phase control mechanism (using splitters) with a geometric path-length-based mechanism (using arm waveguide configurations). This substitution eliminates the wavelength dependence inherent in interferometric splitters while achieving the same phase-difference function through straightforward waveguide length control.
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 achieves reduced loss and minimized phase errors, ensuring consistent 90-degree phase differences across various wavelengths, enhancing the practicality and performance of the 90-degree optical hybrid.
Implementation Method 1
each of the four arm waveguides has a bend waveguide arranged at center thereof and a plurality of optical waveguides including a tapered waveguide having a width that decreases toward the bend waveguide
Implementation Method 2
two optical splitters configured to respectively split inputted light into two beams
Implementation Method 3
two optical combiners configured to respectively combine two beams of inputted light and thereby output two beams of interfering light respectively
Implementation Method 4
each of the four arm waveguides has a bend waveguide arranged at center thereof
Data Source
AI summary
A 90-degree optical hybrid includes two optical splitters that respectively split inputted light into two beams, two optical combiners that respectively combine two beams of inputted light and thereby output two beams of interfering light respectively, and four arm waveguides that input light splitted by any of the two optical splitters into any of the two optical combiners. Each of the four arm waveguides has a bend waveguide arranged at its center and a plurality of optical waveguides including a tapered waveguide having a width that decreases toward the bend waveguide. Both ends of each of the plurality of optical waveguides are respectively in contact with a end surface of any one of the two optical splitter, the two optical combiners, the bend waveguide and the other of the plurality of optical waveguides, and each of the plurality of waveguides is the tapered waveguide or a linear waveguide.