Backreflections in resonant micro-optic gyroscope

Abstract

Backreflection noise is one kind of main optical error in the resonant micro-optic gyroscope (RMOG). Resonance characteristics of backreflection noise in a RMOG is analyzed theoretically. Part of the backreflection noise can not be eliminated by using the traditional phase modulation techniques. This part of backreflection brings a nonzero bias to the output of RMOG due to the asymmetry of resonance curve. Degradation of gyro's linearity is induced because this part's transfer curve has two notches with separation proportional to the Sagnac phase shift when the RMOG is rotating. It's recommended to set the length of straight waveguide to be half the ring length.

Suppression Method of Optical Noises in Resonator-Integrated Optic Gyroscopes

“…Strong backreflection can occur at the interface between an optical fiber and a straight waveguide. The out-cavity back-reflection causes severe degradation on the RIOG [23,72]. Back-reflection noise is commonly decreased by beveling the end faces of components [73] or placing isolators ahead, and the back-reflection coefficient can reduce to about −60 dB [74].…”

“…The shot-noise of the photodetector determines the ultimate sensitivity of the RIOG. However, many characteristics, including backscattering [10][11][12][13][14][15][16][17][18][19][20][21][22], back-reflection [23][24][25][26][27][28], nonlinear Kerr effect [29][30][31][32][33][34][35][36][37], polarization fluctuation [38][39][40][41][42][43][44][45][46][47][48][49][50], and laser frequency noise [51][52][53], have negative impacts. These negative impacts degrade the performance of RIOGs and make it worse than the shot-noise limited theoretical sensitivity.…”