Silicon Waveguide Optical Gyro for Accuracy
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Solution Overview
Problem
Conventional resonator fiber optic gyros (RFOGs) face accuracy issues due to material properties of glass optical fibers, leading to false rotation measurements, high costs, and environmental sensitivity, particularly in miniaturized applications.
Innovation Solution
The use of thin film silicon waveguides on a substrate with a resonator configured to propagate counter-propagating light beams, where the difference in resonance frequencies indicates rotation rate, reducing errors and costs through integrated optics and electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass-based optical fibers are used in RFOG, then light propagation is achieved, but measurement accuracy deteriorates due to material properties causing false rotation indications
Solution Approach 1:
The patent changes the material parameter from glass-based optical fiber to silicon waveguide, fundamentally altering the optical properties and eliminating material-induced errors such as the Kerr effect and Brillouin scattering that cause false rotation indications in conventional RFOGs
Solution Approach 2:
The patent extracts and eliminates the harmful material properties of glass optical fiber by replacing the entire waveguide structure with silicon-based technology, removing the source of measurement errors including temperature sensitivity and non-linear optical effects
2Reliability
If conventional RFOG components are assembled, then functional gyro is created, but manufacturing cost increases due to multiple discrete components
Solution Approach 1:
The patent merges multiple discrete RFOG components (light source, modulator, resonator, detectors) into a single integrated silicon photonic chip, eliminating assembly costs and improving manufacturing efficiency while maintaining functional performance
Solution Approach 2:
The patent replaces mechanical assembly of discrete optical components with monolithic silicon photonic integration, where waveguides, resonators, and other elements are fabricated as a unified structure using semiconductor manufacturing processes
3Volume of moving object
If miniaturization of RFOG components is pursued, then compact size is achieved, but assembly cost and complexity increase
Solution Approach 1:
The patent combines all gyro功能的 elements into a single silicon photonic chip, achieving miniaturization without increasing assembly complexity because the components are fabricated integrally rather than assembled from separate parts
4Measurement precision
If high monochromatic light power is used in RFOG, then resonance frequency measurement is improved, but Kerr effect errors increase altering index of refraction
Solution Approach 1:
The patent changes the waveguide material from glass to silicon, which has different non-linear optical properties that reduce the Kerr effect impact at operating power levels, allowing accurate resonance frequency measurement without significant bias
5Reliability
If fiber couplers are used to circulate light, then light circulation is achieved, but polarization errors are introduced from coupling into second polarization mode
Solution Approach 1:
The patent extracts and eliminates polarization coupling errors by using silicon waveguide structures that maintain single-mode propagation and minimize polarization mode coupling, removing the harmful effect introduced by fiber couplers
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 approach provides a robust, compact, and cost-effective optical gyro with improved accuracy, minimizing bias and angle random walk errors, suitable for high-volume production and small-scale applications.
Implementation Method 1
an optical gyro for measuring a rotation rate... a resonator having first and second counter-propagating directions... Each of the counter-propagating directions having a resonance frequency for light propagation within the resonator. A difference in the resonance frequencies indicating the rotation rate.
Data Source
AI summary
Methods and apparatus are provided for a low cost optical gyro using thin film waveguides to direct light beams among the components of the gyro. The gyro includes a substrate having an insulator layer, a silicon waveguide formed on the insulator layer, and a resonator coupled to the silicon waveguide and configured to circulate a portion of a first light beam in a first counter-propagating direction and circulate a portion of a second light beam in a second counter-propagating direction. The first silicon waveguide propagates the first and second light beams therethrough. Each of the first and second light beams has a resonance frequency when circulating in the resonator.