Crosstalk and phase-noise reduction in time-division multiplexing ofpolarization-insensitive fiber optic Michelson interferometric sensors

摘要

The multiplexing system of fiber optic interferometric sensors suffers from crosstalk and noise, and theperformance degrades. The crosstalk of TDM of the fiber optic interferometric sensor includes lead fibercrosstalk, sensor crosstalk for optical gate with finite extinction ratio (ER) and delay fiber crosstalk. Inthis paper, the laser emission time difference of each interference term of the TDM-PIFOMI system wasutilized to reduce the crosstalk and noise by using laser diode high frequency modulation. The temporalcharacteristics of the crosstalk and the noise of the TDM-PIFOMI system were analyzed, and the theoreticalsensor crosstalk, Asensor, is ?4 ER(dB) by using laser diode high frequency modulation. According to thePGC demodulation process, the minimum frequency of the laser diode modulation was estimated to belarger than nine times of the carrier frequency of the PGC demodulator. In our experimental results, the improvements of the sensor crosstalk were from 8.3 to 15.5 dB, and theimprovements of the delay fiber crosstalk were 15.7 and 14.6 dB by using laser diode high frequency mod-ulation. The phase noise was reduced from 2 dB to 3.9 dB. Using laser diode high frequency modulationto decrease the crosstalk and the noise of the TDM-PIFOMI system is effective and cheap.