A device for providing a bias modulation at a proper frequency to the counterpropagating light waves in the sensing coil of an interferometric fiber optic gyroscope. The photodetector detects the light which has exited the sensing loop, and converts it to an electrical signal that is demodulated by two phase sensitive detector. One phase sensitive detector demodulates the signal that is in phase with the bias modulation signal and the other phase sensitive detector demodulates the quadrature signal with respect to the modulation signal, and controls the frequency of the bias phase modulator driver so as to reduce the quadrature to a minimum and to keep the modulator frequency at the proper frequency of the sensing coil. Increased intensity modulation can be attained with a DC voltage applied to an electrode of the modulator to produce the quadrature signal. In the digital implementation, higher harmonics are introduced to the modulator to increase the quadrature signal for improved sensitivity of the proper frequency of the sensing coil.

Patent Information

Number	US  5734469
Country	US
Status	Issued
Date	03/31/1998