Asymmetric Multi-Ring Resonator for Larger FSR Stability
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Solution Overview
Problem
Existing photonic integrated circuit (PIC) devices face challenges in achieving higher component densities and increased free spectral range (FSR) while minimizing sensitivity to manufacturing process variations, particularly in ring resonators used for wavelength division multiplexing.
Innovation Solution
The implementation of an asymmetric dual or multi-ring resonator configuration with distinct effective lengths and optimized coupling coefficients, including non-circular rings and layered structures, to enhance FSR and reduce sensitivity to manufacturing variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single ring resonator is used, then the device structure is simple, but the free spectral range (FSR) is limited and sensitivity to manufacturing variations is high
Solution Approach 1:
The patent divides a single ring resonator into multiple coupled ring resonators with different effective lengths. This segmentation allows each ring to contribute differently to the overall FSR, enabling a larger composite FSR while maintaining manufacturing tolerance through the distributed design. The coupling between segments creates the desired spectral filtering characteristics.
Solution Approach 2:
The patent employs asymmetric ring resonators with deliberately different effective lengths rather than identical symmetric rings. This asymmetry in the multi-ring configuration creates distinct resonance conditions that expand the overall FSR and reduce sensitivity to manufacturing variations, as the different length rings respond differently to dimensional tolerances.
2Reliability
If the FSR is increased by using smaller rings, then the FSR increases, but the sensitivity to manufacturing process variations increases
Solution Approach 1:
Instead of using a single small ring that would have high sensitivity, the patent segments the resonator function across multiple rings with different sizes. The smaller rings provide the necessary FSR expansion while the larger rings contribute to reduced sensitivity, and their coupling creates the overall desired performance with reduced manufacturing sensitivity.
Solution Approach 2:
The patent changes the parameter of effective length across multiple rings rather than keeping all rings identical. By varying the effective lengths of different rings in the coupled system, the patent achieves FSR expansion while the diversity in parameters reduces the overall sensitivity to manufacturing variations in any single ring.
3Productivity
If component density is increased in PIC devices, then the integration level increases, but the complexity of achieving precise optical coupling and maintaining performance increases
Solution Approach 1:
The patent combines multiple ring resonators into a single integrated optical coupling structure that interfaces with the waveguide. This merging allows the coupled multi-ring system to be treated as one functional unit for coupling purposes, simplifying the interface design while maintaining the benefits of multiple rings for FSR and sensitivity performance.
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 asymmetric multi-ring resonator design achieves a significantly larger FSR with improved filtering capabilities and reduced sensitivity to manufacturing process variations, ensuring effective signal transmission and differentiation between resonant and side modes.
Implementation Method 1
ring resonators have the property of selectively transmitting signals at wavelengths corresponding to their primary resonance modes and attenuating or blocking signals at other wavelengths
Implementation Method 2
The asymmetric multi-ring resonator design achieves a significantly larger FSR with improved filtering capabilities and reduced sensitivity to manufacturing process variations, ensuring effective signal transmission and differentiation between resonant and side modes
Data Source
AI summary
A photonic integrated circuit has an asymmetric dual ring resonator. The asymmetric dual ring resonator includes a first ring having a first effective length and a second ring having a second effective length, which is distinct from the first effective length. The first effective length and the second effective length are near integer multiples of a third effective length. The third effective length is within about an order or magnitude of the first effective length and the second effective length. The asymmetric dual ring resonator has a free spectral range corresponding to a single ring resonator having the third effective length but has a lower sensitivity to manufacturing process variations than would a single ring resonator having the third effective length.