Silicon Nitride Waveguide Optical Gyroscope Hybrid Phase Shifter
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Solution Overview
Problem
Conventional fiber optical gyroscopes (FOGs) are large, expensive, and difficult to assemble due to the need for precise alignment of discrete optical components, making them challenging for volume production and integration into compact systems.
Innovation Solution
A multi-layer silicon nitride waveguide-based integrated photonics optical gyroscope with a rotation sensing element and a front-end chip, where the phase shifter can be fabricated on a separate material platform and hybridly integrated, allowing for a compact and scalable design with reduced vertical crosstalk and increased manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fiber optical gyroscopes are constructed using discrete optical components, then measurement precision is improved, but device complexity and ease of manufacture deteriorate due to the need for precise manual alignment
Solution Approach 1:
The patent combines multiple discrete optical components (waveguides, phase shifters, modulators, detectors) into a single integrated photonic chip. This integration maintains the precise optical paths needed for measurement while eliminating manual alignment requirements, as all components are fabricated in fixed relative positions using semiconductor manufacturing processes.
Solution Approach 2:
The patent replaces mechanical alignment and assembly processes with photolithographic fabrication processes. Instead of manually positioning and aligning discrete components, all optical elements are patterned and integrated onto the chip using standard semiconductor manufacturing techniques, enabling automated high-volume production.
2Measurement precision
If fiber optical gyroscopes use discrete optical components, then measurement precision is improved, but productivity deteriorates due to difficulty in volume production
Solution Approach 1:
By integrating all optical components onto a single chip, the system enables parallel fabrication of multiple units using semiconductor wafer processing techniques. This eliminates the sequential manual assembly required for discrete component systems, dramatically increasing production throughput and enabling cost-effective volume manufacturing.
3Device complexity
If phase shifters are integrated on the same material platform as waveguides, then device complexity is reduced, but manufacturing precision deteriorates due to material compatibility constraints
Solution Approach 1:
The patent employs a multi-layer composite material structure where silicon nitride waveguides are fabricated on one layer and piezoelectric phase shifters are deposited on a separate layer. This layered composite approach allows each material to be optimized for its specific function while maintaining precise spatial relationships through controlled deposition processes, achieving both integration and fabrication precision.
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 enables the creation of compact, high-precision optical gyroscopes with reduced size, weight, and cost, suitable for applications like autonomous vehicles, by leveraging silicon nitride waveguides and hybrid integration of phase shifters, facilitating mass production and integration into inertial measurement units.
Implementation Method 1
Optical gyroscopes typically have the highest performance and are based on interferometric measurements and the Sagnac effect (a phenomenon encountered in interferometry that is elicited by rotation)
Implementation Method 2
an integrated photonics optical gyroscope fabricated on a silicon nitride (SiN) waveguide platform comprises a first layer of silicon nitride (SiN) waveguides
Implementation Method 3
Phase shifters can be of electro-optic materials such as lithium niobate or other polymers
Implementation Method 4
Phase shifters can also be made of piezo-electric materials such as aluminum nitride (AlN) or strontium bismuth titanate (SBT)
Data Source
AI summary
An integrated photonics optical gyroscope fabricated on a silicon nitride (SiN) waveguide platform comprises a first silicon nitride (SiN) waveguide layer that constitute a rotation sensing element; and, a second SiN waveguide layer with additional silicon nitride (SiN) waveguide-based optical components that constitute a front-end chip to launch light into and receive light from the rotation sensing element. The two SiN waveguide layers can be stacked together to have a multi-layer configuration vertically coupled with each other. External elements (e.g., laser, detectors, phase shifter) may be made of different material platform than SiN and can be hybridly integrated to the SiN waveguide platform. The phase shifters can be made of aluminum nitride (AlN) or strontium bismuth titanate (SBT).