Broadband Resonator Optical Gyroscope With Sawtooth Phase Control
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Solution Overview
Problem
Narrow linewidth laser sources in resonator fiber optic gyroscopes (RFOGs) are susceptible to optical Kerr effects, leading to weak output signals, while broadband laser sources cause power loss due to narrow resonance peaks, making detection challenging, and acousto-optic modulators are bulky and expensive, unsuitable for small-scale designs.
Innovation Solution
A closed-loop optical gyroscope using a broadband light source with adaptive sawtooth phase modulation compensates for power losses by adjusting the phase modulator based on feedback, maintaining a constant power response and scale factor linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a narrow linewidth laser source is used in RFOG, then the optical Kerr effects are reduced, but the output signal becomes weak
Solution Approach 1:
The patent changes the fundamental parameter of the light source from narrow linewidth to broadband, which fundamentally alters the interaction with the optical resonator. The broadband source generates multiple frequency components that can be selectively resonated, transforming the weak single-frequency output into a stronger multi-frequency output while maintaining reduced Kerr effects.
Solution Approach 2:
The broadband laser source is effectively segmented into multiple frequency components or modes. These segmented frequency components are then individually managed through the optical resonator's frequency-selective properties, allowing each component to contribute to the overall signal strength while the resonator filters out unwanted components.
2Object-affected harmful factors
If a broadband laser source is used in RFOG, then the optical Kerr effects are reduced, but power loss occurs due to narrow resonance peaks
Solution Approach 1:
The patent employs a feedback mechanism where the output of the optical resonator is fed back to the broadband laser source. This feedback loop allows the system to dynamically adjust the laser's emission characteristics to match the resonator's resonance conditions, thereby maximizing power transfer and minimizing energy loss despite the broadband nature of the source.
Solution Approach 2:
The system transitions from a static narrow linewidth source to a dynamic broadband source that can adapt its spectral characteristics. The broadband source's ability to dynamically adjust its emission spectrum allows it to track the resonator's resonance frequencies, ensuring continuous efficient power transfer even as resonance conditions change.
3Ease of operation
If acousto-optic modulators are used for phase modulation, then phase modulation is achieved, but the device becomes bulky and expensive
Solution Approach 1:
The patent replaces the mechanical/acoustic-based acousto-optic modulator with an electro-optic modulator. This substitution eliminates the need for acoustic waves and mechanical moving parts, thereby reducing the device size, eliminating bulkiness, and reducing cost while maintaining the essential phase modulation functionality through electrical control of optical properties.
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 system reduces optical Kerr effects and maintains stable rotation rate determination by using a broadband light source with electro-optic phase modulators, ensuring reliable signal detection and precise rotation rate measurements.
Implementation Method 1
The phase modulator is configured to generate a phase-modulated optical signal from the optical signal based on a sawtooth modulation signal
Implementation Method 2
The resonance frequencies of the optical resonator are frequency-shifted due to the Sagnac effect when the RFOG experiences a rotation about its sense axis
Implementation Method 3
a broadband light source configured to generate an optical signal having a broadband frequency range
Data Source
AI summary
Various examples of a closed-loop optical gyroscope are disclosed. The closed-loop optical gyroscope includes a broadband light source configured to generate broadband optical signal(s). The broadband optical signal(s) propagate in an optical resonator and are coupled in and out of the optical resonator by optical couplers. A phase modulator applies phase modulation to the optical signal(s) based on a sawtooth modulation signal. The optical signal(s) repropagate in the optical resonator in a different direction. The optical signal(s) are then received and analyzed to determine parameter(s) of the phase modulator. One or more processors configure the phase modulator based on the determined parameter(s).