Abstract
Aiming at the severe inter-channel crosstalk and degraded detection accuracy existing in wavelength division multiplexing (WDM)-based fiber Fabry–Perot (F-P) sensor arrays, this paper proposes a multi-channel WDM crosstalk suppression technique based on phase-shifting diversity demodulation. A theoretical crosstalk model is constructed, and analysis reveals that WDM crosstalk depends on four key parameters: wavelength diversity group number k, channel extinction ratio ε, amplitude of the measured signal As, and wavelength interval m. Numerical simulations and experiments are performed on a dual-channel WDM sensing system to evaluate the influences of these parameters on the crosstalk suppression performance. Results verify that the proposed crosstalk suppression technique can remarkably suppress inter-channel crosstalk compared with the system without crosstalk suppression, and the fundamental-frequency crosstalk suppression level is improved by 33.8 dB. For engineering optimization, there exist an optimal wavelength diversity group number and an optimal wavelength interval to achieve maximum crosstalk attenuation. Moreover, the proposed technique relaxes the strict extinction ratio requirements for WDM devices and mitigates the hardware limitations in large-scale array systems. This method effectively addresses the crosstalk bottleneck of fiber F-P sensor arrays under WDM configuration, and provides theoretical guidance and an engineering optimization strategy for large-scale underwater fiber F-P WDM sensing arrays.