Optical Resonator-Waveguide Coupling Without Adhesive Gaps
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Solution Overview
Problem
Existing optical circuits face challenges in accurately controlling the distance between a whispering gallery mode resonator and an optical waveguide, which is crucial for stable optical coupling. Adhesives used for fixation are sensitive to temperature changes, leading to instability in the coupling.
Innovation Solution
The optical circuit design includes an optical waveguide with a ridge on a substrate and a whispering gallery mode resonator. The resonator is positioned such that a part of its light circulating surface faces the upper surface of the ridge with a controlled first gap in between, ensuring the distance is shorter than the evanescent wave leakage distance, thus achieving stable optical coupling without the need for adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If adhesive is used to fix the resonator to the optical waveguide, then the resonator can be positioned, but the distance control accuracy deteriorates due to adhesive thickness variation and temperature sensitivity
Solution Approach 1:
The invention removes the adhesive layer from the optical coupling structure, extracting the problematic element that caused distance control inaccuracies. The resonator is positioned above the optical waveguide without adhesive, eliminating thickness variation and temperature sensitivity issues while maintaining mechanical support through alternative means.
Solution Approach 2:
The invention employs a thin film structure where the resonator is positioned close to the optical waveguide surface without requiring adhesive bonding. This thin-film approach enables precise distance control through evanescent wave coupling while avoiding the complications of adhesive layer management.
2Reliability
If the distance between resonator and optical waveguide is reduced for better coupling, then optical coupling efficiency improves, but the system becomes more sensitive to temperature changes and vibrations
Solution Approach 1:
The invention introduces the evanescent wave as an intermediary field that enables optical coupling without direct physical contact between the resonator and optical waveguide. This field-mediated coupling allows efficient energy transfer while maintaining a small air gap that reduces sensitivity to temperature and vibrations compared to adhesive-based coupling.
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 allows for stable and accurate optical coupling between the resonator and the optical waveguide, reducing the impact of temperature changes and vibrations, and enhancing the reliability of the optical circuit.
Implementation Method 1
a distance between the part of the light circulating surface and the upper surface of the ridge facing the part of the light circulating surface is shorter than a distance at which an evanescent wave leaks
Data Source
AI summary
An optical circuit includes a resonator and an optical waveguide that includes a ridge formed upon substrate or a semiconductor layer. The resonator has a light circulating surface and is disposed such that part of the light circulating surface faces the upper surface of the ridge, across a first gap. The distance between part of the light circulating surface and the upper surface of the ridge facing the part of the light circulating surface is shorter than the distance that an evanescent wave protrudes.