光纤环形腔激光陀螺中的闭锁效应

Lock-in Effect in Fiber Ring Laser Gyros

通过理论分析,得到了掺铒光纤环形腔激光陀螺中存在后向反射时,陀螺的两束激光频差和陀螺转速动态关系的解析表达式,并用矢量图明确表明了闭锁效应出现的条件。分析表明光纤激光陀螺的闭锁主要是由瑞利后向散射引起的,这一散射虽然在红外波长甚弱,但在有源环形腔内会被显著加强,因此成为陀螺闭锁的主要原因。实验证实了上述理论分析结果,在陀螺旋转速度小于10°/s时出现了闭锁。

Taking account of the backscattering in a ring cavity,resonance behavior of two counter-propagating lasing beams is analyzed and the dynamic lasing frequencies as a function of rotation rates are obtained in a close form.The condition for occurring lock-in effect in the gyro is also obtained easily from the vector diagrams.It is noted that the Rayleigh backscattering is the main source to form the lock-in effect,although the scattering is weak in a fiber at infrared wavelength,which can be considerably enhanced in an active resonator.The above mentioned analytic close form of dynamic frequencies is confirmed by a fiber ring laser gyro experiment,and the gyro is locked-in when its rotation rate is less than 10° /s.