The Study Of Resonant Frequency Tracking And Locking Technique Based On High Quality Microcavity

The high quality microcavity has been widely used in many fields for its extreme highquality and small volume. Resonant optical gyro based on microcavity has unique advantagein the miniaturization and integration. The frequency tracking and locking technique is thekey to realize the signal detection of high precision resonant gyro. The research was carriedout aimed to the problem of resonant frequency tracking and locking in this paper. And deepanalysis about the phase modulation and demodulation technique was presented as the mostkey aspect in the resonant point tracking and locking problem.The modulation and demodulation characteristics of microcavity were analyzedtheoretically and simulation of sine wave modulation was presented. Meanwhile, the effect ofdifferent modulation signals, such as sawtooth wave, triangle wave and sine wave, was tested.Reset pulse problem in sawtooth wave modulation experiment and square wave overshootphenomenon in triangle wave modulation experiment were analyzed and the comparision ofsignal noise rations of resonant signals modulated by the three different waveforms. The sinewave was chose to be the modulation waveform in the system. To testify the feasibility ofsine wave modulation, the modulation experiment about fiber ring resonator was carried outand the low frequency modulation curve and the sideband curve under high frequencymodulation were obtained which proved the feasibility of sine wave modulation method.Finally, the modulation and demodulation of microcavity with sine wave was realized in thesystem proposed in this paper.Meanwhile, the theoretical analysis about ripple noise in the modulation anddemodulation system based on microcavity was carried out. The theory of ripple noise wasproposed and its characteristics, for example resonance-like feature, top-gathering feature andrandom walk feature, were analyzed. The suppression methods including the suppression ofend face reflection and phase modulation suppression were also presented which were proved to be effective to eliminate the ripple noise in the system.In the end, the resonant frequency tracking and locking system based on microcavity wasproposed. Resonant signals both modulated and demodulated were tested in the system. Theresonant frequency tracking and locking realized with the use of PID feedback controller anddemodulation signal. The frequency stability was1.66×10-8in10s.