INTERFEROMETRIC FIBER SENSORS BASED ON TRIANGULAR PHASE MODULATION

This work presents three novel signal processing methods capable of ac curately detecting the optical phase delay in optical interferometric sensors. In the proposed methods, a triangular waveform modulation sig nal is used to modulate the optical phase of an optical interferometer for measuring optical phase delay. The optical phase delay in the fir st method is obtained by integrating the interferometric output signal s with the gated-in signal. The optical phase delay in the second meth od can be measured from the time delay difference between the interfer ometric signals during the gated-in period. For the third method, the pseudo-heterodyne technique is applied, and the optical phase delay is measured from the phase difference between two output signals. Moreov er, a fiber Sagnac interferometric rotation sensor is adopted to demon strate the effectiveness of the proposed methods. Furthermore, experim ental results confirm that the proposed methods have an extreme degree of sensitivity and good linearity.