SiN Ring-Waveguide Optical Gyroscope with Balanced Detection
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Solution Overview
Problem
Fiber-based gyroscopes are bulky, expensive, and hard to assemble due to the need for precise alignment of discrete optical components, making them unsuitable for volume production.
Innovation Solution
Replace fiber-based components with silicon nitride (SiN) waveguide-based microresonators integrated on a semiconductor platform, using a balanced detection scheme to cancel noise and enhance sensitivity, incorporating a hybrid integration of a narrow linewidth laser with SiN microresonators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fiber-based gyroscopes are used, then high measurement precision is achieved, but device size becomes bulky and manufacturing complexity increases
Solution Approach 1:
The patent replaces mechanical fiber-optic components with an integrated photonic chip that uses on-chip waveguides and microresonators. This substitution of mechanical fiber systems with integrated photonic structures reduces the device footprint while maintaining the Sagnac effect-based optical interference mechanism for precise angular velocity sensing
Solution Approach 2:
The patent merges multiple discrete optical components (lasers, modulators, detectors, and optical paths) into a single integrated photonic chip. This consolidation integrates the light source, modulation elements, sensing waveguides, and detection circuits onto one chip, dramatically reducing the overall device size while preserving measurement precision
2Measurement precision
If fiber-based gyroscopes are used, then high measurement precision is achieved, but device complexity and assembly difficulty increase
Solution Approach 1:
The patent replaces complex mechanical alignment and assembly of discrete fiber-optic components with a monolithic integrated photonic chip fabrication process. Standard semiconductor manufacturing techniques are used to create precisely aligned waveguides and optical elements directly on the chip, eliminating the need for manual fiber alignment and complex mechanical assembly
Solution Approach 2:
The patent segments the gyroscope functionality into distinct integrated photonic components (laser source, modulation section, sensing ring resonators, detection photodiodes) that are fabricated separately and then combined through standardized bonding processes. This modular segmentation simplifies the overall manufacturing and assembly process compared to traditional fiber-based approaches
3Measurement precision
If fiber-based gyroscopes are used, then high measurement precision is achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive, labor-intensive manual assembly of precision fiber-optic components with scalable semiconductor manufacturing processes. Standard photolithography, etching, and deposition techniques used in the semiconductor industry enable high-volume production of integrated photonic gyroscopes at lower cost while maintaining precise optical alignment
Solution Approach 2:
The patent changes the manufacturing parameters from manual, low-volume fiber optic assembly to automated, high-volume semiconductor fabrication. This parameter change in the manufacturing process enables economies of scale, reducing the cost per unit while maintaining the high measurement precision required for gyroscope operation
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
Achieves a compact, low-loss, and cost-effective optical gyroscope with high sensitivity and performance equivalent to fiber optic gyroscopes, suitable for volume production and applications like inertial measurement units in autonomous vehicles.
Implementation Method 1
rotation-induced resonance frequency shift due to the Sagnac effect is much more prominent that the FOGs
Implementation Method 2
interferometric measurements of optical phase shift due to the Sagnac effect
Data Source
AI summary
The present disclosure relates to integrated photonics-based optical gyroscopes with silicon nitride (SiN) waveguide-based microresonators. SiN microresonators are fabricated either on a fused silica platform or on a silicon substrate with oxide cladding. A narrow linewidth high-Q laser is hybridly integrated on a silicon photonics platform. The laser is tuned with a first SiN microresonator, and the rotational sensing component of the gyroscope comprises another SiN microresonator. The silicon photonics front-end chip has components for a balanced detection scheme to cancel noise in the optical signal coming back from the rotational sensing component.