Gain-Coupled Resonator Gyroscope for High Sensitivity

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Solution Overview

Problem

High-accuracy optical gyroscopes face challenges in compactness and sensitivity due to the large size and weight of fiber optic gyroscopes, and previous enhancements using coupled resonant optical waveguides have been overstated or based on incomplete definitions of sensitivity, which do not account for all parameters affecting the gyroscope's precision.

Innovation Solution

A gain-coupled resonator gyroscope with parity-time symmetry, comprising two ring resonators with one having a gain and the other a loss, operates away from the exceptional point to achieve higher sensitivity by optimizing the inter-resonator coupling rate and gain, enhancing the rotation-induced shift and power circulation, thereby improving the gyroscope's sensitivity beyond what is achievable at the exceptional point.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If fiber coils with very large area are used to achieve high rotation sensitivity, then the Sagnac phase shift is sufficient for measurement, but the size, weight, and material costs increase significantly

Engineering Contradiction:
Improverotation sensitivityVSAvoidgyroscope weight
Core Design Contradiction:
Measurement precisionVSWeight of stationary object

Solution Approach 1:

The single large fiber coil is segmented into multiple smaller ring resonators that are optically coupled together. This segmentation allows the system to achieve the equivalent optical path length of a large coil while using much shorter physical fiber lengths, thereby reducing weight and size while maintaining rotation sensitivity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple ring resonators are nested or coupled in a cascaded configuration where light circulates through each resonator sequentially. This nesting approach accumulates the Sagnac phase shift across multiple resonators, achieving the sensitivity of a long fiber coil with compact individual resonator units.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Measurement precision

If fiber coils with very large area are used to achieve high rotation sensitivity, then the Sagnac phase shift is sufficient for measurement, but the device size increases significantly

Engineering Contradiction:
Improverotation sensitivityVSAvoidgyroscope area
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The large area requirement is segmented into multiple smaller resonator areas. By coupling several compact ring resonators, the system achieves the effective sensing area equivalent to a large single coil without the corresponding physical footprint, enabling compact gyroscope design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system transitions from a single-plane large-area coil to a multi-resonator configuration that can be arranged in three-dimensional space or stacked configurations, effectively utilizing spatial dimensions to reduce the projected area while maintaining the optical path length for sensitivity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Measurement precision

If coupled resonant optical waveguides are used to enhance rotation sensitivity, then the sensitivity improvement is claimed, but the claims are erroneous or based on incomplete definitions

Engineering Contradiction:
Improverotation sensitivityVSAvoidsensitivity measurement accuracy
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements a comprehensive sensitivity definition that incorporates feedback from multiple parameters including circulating power, resonance quality factor, and coupling coefficients. This multi-parameter feedback approach ensures accurate and reliable sensitivity measurements that account for all system characteristics, avoiding the erroneous claims of previous studies.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system optimizes multiple parameters simultaneously including the coupling coefficients between resonators, the circulating power levels, and the resonance frequencies. By systematically adjusting these parameters and their interrelationships, the patent achieves reliable sensitivity enhancement with accurate measurements, correcting the incomplete parameter considerations in prior work.

Inventive Principle:
Principle #35Parameter changes

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 gyroscope achieves a rotation sensitivity enhancement factor of up to 170 times that of a single-ring gyroscope, with a minimum detectable rotation rate significantly improved, demonstrating enhanced precision and compactness.

Implementation Method 1

High-accuracy optical gyroscopes rely on the Sagnac effect, which produces a phase shift in the light traveling along a length of fiber that is rotated.

Methodology Applied
Scientific EffectSagnac effect: Sagnac Effect

Implementation Method 2

In such a resonator, light recirculates many times, picking up a Sagnac phase shift at each recirculation, thereby accumulating a much greater total rotation-induced phase-shift

Methodology Applied
Scientific EffectOptical resonance: Resonance

Data Source

PatentEP3918277B1Gain-coupled resonator gyroscope
Publication Date: 2023.12.06 THE BOARD OF TRUSTEES OF THE LELAND STANFORD JUNIOR UNIV
  • EP3918277B1 patent drawingFigure 1A
  • EP3918277B1 patent drawingFigure 1B
  • EP3918277B1 patent drawingFigure 1C

AI summary

A gyroscope includes a first optical resonator in optical communication with at least one optical waveguide and a second optical resonator in optical communication with the first optical resonator. One of the first optical resonator and the second optical resonator has a power loss rate L greater than zero and the other of the first optical resonator and the second optical resonator has a power gain rate G greater than zero. The at least one optical waveguide, the first optical resonator, and the second optical resonator are configured to be below lasing threshold. The gyroscope further includes at least one optical detector in optical communication with the at least one optical waveguide, and the at least one optical waveguide is configured to receive, from at least one light source, light having an input power P in at a frequency ω p and to transmit at least a portion of the light having an output power P out to the at least one optical detector.