Passive quadrature demodulation of multiplexed interferometric sensors using a CW correlation reflectometer with a single DFB diode laser.

In this Letter, we report a novel, to the best of our knowledge, and simple approach for passive quadrature-phase demodulation of relatively long multiplexed interferometers based on two-channel coherence correlation reflectometry. Two-wavelength channels are generated using a single unmodulated CW-DFB diode laser and an acousto-optic frequency shifter. The introduced frequency shift determines the optical lengths of the interferometers.