Variable-Width Optical Ring Resonator for Stable Wavelengths
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Solution Overview
Problem
Optical ring resonators are susceptible to manufacturing variations in waveguide width and etch-depth nonuniformities, leading to shifts in resonant wavelength and compromising their performance.
Innovation Solution
The optical ring resonator employs a variable geometry optical waveguide loop with angle-dependent inner and outer radii, configured to couple fundamental and higher order modes, reducing sensitivity to etch variations and utilizing less thermal tuning power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional optical ring resonator with constant waveguide width is used, then the device structure is simple, but the resonant wavelength is sensitive to manufacturing variations and etch-depth nonuniformities
Solution Approach 1:
The waveguide width is varied locally along the optical path rather than being uniform throughout. Specifically, the waveguide width is narrower at coupling regions and wider at other regions, creating local variations that compensate for manufacturing variations and stabilize the resonant wavelength against etch-depth nonuniformities.
Solution Approach 2:
The waveguide geometry transitions from a symmetric constant-width structure to an asymmetric variable-width structure. The width varies as a function of position along the optical path, breaking the symmetry to achieve insensitivity to manufacturing variations while maintaining functional performance.
2Reliability
If thermal tuning is applied to compensate for wavelength shifts, then the resonant wavelength can be adjusted, but the power consumption increases and self-heating occurs
Solution Approach 1:
Instead of using thermal tuning to compensate for manufacturing variations, the invention converts the manufacturing variations themselves into a beneficial feature. The variable waveguide width is designed to inherently compensate for etch-depth nonuniformities, eliminating the need for thermal tuning and its associated power consumption and self-heating problems.
3Reliability
If the waveguide width is varied to couple fundamental mode to higher order modes, then the sensitivity to etch depth variations is reduced, but the device complexity increases
Solution Approach 1:
The waveguide width parameter is changed along the optical path to achieve mode coupling. By varying the width from narrow to wide regions, the device couples fundamental mode to higher order modes, which provides insensitivity to etch depth variations while maintaining a relatively simple geometric structure.
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
The solution provides stable resonant wavelength operation with reduced thermal power consumption and self-heating, enhancing device performance and compatibility with CMOS manufacturing.
Implementation Method 1
the optical waveguide loop may be configured to couple a fundamental mode to a plurality of higher order modes propagating within the optical waveguide loop
Implementation Method 2
the optical waveguide loop has an inner radius, and the inner radius has a length that is variable along the path of the optical waveguide loop
Data Source
AI summary
Some embodiments of the present disclosure are directed to an optical device including a stable optical waveguide loop and method of manufacturing the same. For example, an optical device (e.g., an optical ring resonator) may include a substrate and an optical waveguide loop formed on the substrate. The optical waveguide loop may define a path, where the optical waveguide loop may have an inner and outer radius that may be configured to be variable along the path of the optical waveguide loop. Further, a distance between the inner radius and a corresponding outer radius may define a width of the optical waveguide loop, where the width may be variable along the path of the optical waveguide loop. Additionally, or alternatively, the width may be configured to admit a plurality of higher order modes of light that may couple to a fundamental mode of light.