Resonant fiber optic gyroscope coherent demodulation system and method based on external beam interference

Abstract

The invention discloses a resonant type fiber-optic gyro coherent demodulation system and method based on interference of externally added light beams. The system includes a laser, a first polarization-maintaining coupler, a Y-branch phase modulator, a phase modulator, an optical fiber resonant cavity, a second polarization-maintaining coupler, a third polarization-maintaining coupler, a first photoelectric detector, a first band-pass filter, a local carrier generation module, a first local carrier phase shift module, a first 90-degree phase shift module, a first multiplier, a second multiplier, a first low-pass filter, a second low-pass filter, a third multiplier, a third low-pass filter, a first digital phase-lock amplifier, a PI servo loop, a fourth polarization-maintaining coupler, a second photoelectric detector, a second band-pass filter, a second local carrier phase shift module, a second 90-degree phase shift module, a fourth multiplier, a fifth multiplier, a fourth low-pass filter, a fifth low-pass filter, a sixth multiplier, a sixth low-pass filter, and a second digital phase-lock amplifier. By local recovery of a carrier with high signal-to-noise ratio, the signal-to-noise ratio of a demodulated signal is improved, the influence of laser frequency noise is reduced, and the resonant type fiber-optic gyro coherent demodulation system and method have important scientific significance and application value.

Description

technical field [0001] The invention relates to a resonant optical fiber gyroscope demodulation system and method for locking an optical passive resonant cavity resonant cavity by interference of externally applied coherent light, so as to suppress laser frequency noise in the resonant optical fiber gyroscope. Background technique [0002] The resonant fiber optic gyro is an inertial angular velocity sensor based on the Sagnac effect. It uses the frequency difference between the clockwise and counterclockwise resonant frequencies of the resonant cavity caused by the Sagnac phase shift generated by the rotation to measure the rotational angular velocity. Compared with the interferometric fiber optic gyroscope, the resonant fiber optic gyroscope uses the laser to transmit multiple times in the resonant cavity to amplify the Sagnac effect, and achieve the same limit sensitivity as the interferometric fiber optic gyroscope with shorter optical fibers. It has the characteristics ...

AI Technical Summary

Problems solved by technology

[0006] From the perspective of system miniaturization, a semiconductor laser with a smaller volume is more suitable as a system light source for a resonant fiber optic gyroscope, but the semiconductor laser itself has greater frequency noise than a fiber laser, and the PDH laser frequency locking technology is limited Due to the noise suppression bandwidth, it only has a good suppression effect on frequency noise at low frequencies, and has no suppression effect on white noise at high frequencies.

Therefore, the existing laser frequency noise suppression scheme cannot completely suppress the laser frequency noise in the miniaturized resonator fiber optic gyroscope

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