Open-loop fiber-optic gyroscope using intensity-modulated source and phase modulation

A simple open-loop approach to a standard fiber-optic gyroscope that uses an intensity-modulated source is described. Direct readout of the Sagnac effect in an open-loop form is obtained by applying a sinusoidal modulation to the source and the phase modulator at the proper frequency, with the modulation depth of the source adjusted appropriately. Experimental results show good linearity over a wide dynamic range.