Reduction of light-source-induced scale-factor nonlinearities in low-cost fiber optic gyroscope

Laser diodes in sub-threshold regime are used as low- coherent broadband light sources in low-cost interferometric fiber-optic gyroscopes with better than 2 degrees/h bias repeatability over -30 degrees...+70 degrees C temperature range. The optical reflectivity of the laser diode causes nonlinear contributions to the interferometer output signal. Corresponding to theoretical calculations, the scale factor error varies in dependence on the actual rotation rate. This error for the present has been reduced to about 30 percent applying an active compensation of the light reflected in the laser diode.