Multi-Axis Fiber Optic Gyroscope PIC Layout for Splice-Free IMUs
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Solution Overview
Problem
Conventional inertial measurement units (IMUs) using multiple fiber optic gyroscopes require large space and laborious fiber placement, affecting optical performance and increasing production complexity.
Innovation Solution
A photonic integrated circuit (PIC) layout that groups optical interfaces on one or more facets for connection to optical fiber arrays, eliminating individual splices and enabling high-yield, high-throughput manufacturing of multi-axis fiber optic gyroscope systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional individual optical circuits with discrete components are used, then each circuit can be independently designed and assembled, but the overall device size becomes large and requires extensive fiber placement space
Solution Approach 1:
The patent merges multiple discrete optical circuits onto a single photonic integrated circuit substrate. Multiple optical circuits that were previously implemented as separate assemblies with individual components (light sources, couplers, detectors, fiber coils) are now integrated into one compact PIC device, dramatically reducing the overall device size and eliminating the need for extensive external fiber placement while maintaining independent circuit functionality.
Solution Approach 2:
The patent transitions from a three-dimensional assembly of discrete components requiring significant spatial volume to a two-dimensional planar integration on a PIC substrate. This dimensional change allows multiple optical circuits to be packed closely together on a flat surface, reducing the device footprint from tens of meters of fiber space to a compact integrated circuit form factor.
2Adaptability or versatility
If individual fiber optic circuits with multiple splices are used, then component flexibility is maintained, but manufacturing complexity and time increase significantly
Solution Approach 1:
The patent performs preliminary integration of multiple optical circuits onto the PIC substrate during manufacturing, before final assembly. The optical circuits are pre-configured with their respective components (light sources, couplers, detectors, waveguides) already connected through on-chip interconnections, eliminating the need for post-manufacturing splicing and alignment operations, thereby dramatically increasing manufacturing throughput.
Solution Approach 2:
The patent replaces mechanical splicing and manual alignment operations with automated photolithography and deposition processes used in standard semiconductor manufacturing. The optical circuits are defined and interconnected through patterned waveguides and coupling structures created by photomasks and deposition techniques, substituting labor-intensive mechanical assembly with high-speed automated fabrication processes.
3Adaptability or versatility
If optical interfaces are distributed across multiple locations on the PIC, then circuit layout flexibility is improved, but fiber placement complexity and optical performance degradation increase
Solution Approach 1:
The patent implements local grouping of optical interfaces on the PIC substrate, where interfaces are clustered in specific regions optimized for their function. This local quality approach allows the PIC to maintain different interface densities and configurations in different areas, optimizing both fiber placement simplicity and optical performance by keeping related interfaces close together while maintaining overall circuit flexibility.
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 PIC layout reduces the size of IMUs by an order of magnitude, improves manufacturing efficiency, and maintains optical performance parameters like optical loss and polarization extinction ratio (PER).
Implementation Method 1
The optical circuits may be implemented with waveguides, couplers, splitters, modulators, detectors, and other optical components known in the art
Implementation Method 2
The optical couplers 104, 108 typically comprise either single mode or polarization maintaining optical fibers that are fused and/or constructed to provide light splitting capabilities
Implementation Method 3
a PZT optical modulator 112
Data Source
AI summary
A photonic integrated circuit (PIC) comprises at least two optical circuits disposed on the PIC, two or more optical interfaces each configured to provide a connection to at least one external optical component, and a layout arrangement of the at least two optical circuits on the PIC, the layout arrangement configured such that the two or more optical interfaces are situated in at least one local group of optical interfaces, and the at least one local group of optical interfaces is located on at least one facet of the PIC. The at least two optical circuits may comprise a set of N single-axis 2×2 optical fiber optic gyroscope (FOG) circuits for use as a multi-axis FOG assembly in an inertial management unit (IMU) or an inertial navigation system (INS).