High-quality hybrid TDM/DWDM-based fiber optic sensor array with extremely low crosstalk based on wavelength-cross-combination method

Abstract

A high-quality hybrid time-division-multiplexing (TDM)/dense wavelength-division-multiplexing (DWDM)-based fiber optic sensor array with extremely low crosstalk is proposed and experimentally demonstrated in this paper. The array is based on a novel wavelength-cross-combination (WCC) method, aiming to combat the annoying problem of crosstalk between adjacent sensors. The core idea of this method is to reassign optical pulses of different wavelengths rather than of the same wavelength to the same photodetector to eliminate the possibility of coherent optical pulse overlapping and interference. Based on the WCC method and a so-called rectangular-pulse binary phase demodulation scheme, a sensor array with 4 TDM time windows and 16 DWDM wavelengths is set up and experimentally tested. Test results show that even utilizing an optical pulse modulator with less than 28 dB extinction ratio, the obtained crosstalk between adjacent sensors can be still suppressed down to less than −60 dB. This method provides an excellent choice for a practical sensor array application where the sensing performance is of the top consideration.