Multi-Channel OFDR Strain Sensor Based on Wavelength/Space Division Multiplexing Weak FBG Arrays

A multi-channel OFDR strain sensor was demonstrated based on femtosecond-laser-inscribed wavelength/space division multiplexing weak fiber Bragg grating array (WFBGA) in standard SMF. At a sensing spatial resolution of 3 mm, the number of channels and the measurement strain range were eight and 9000 µϵ, respectively. The reflection spectral of each WFBG for each channel were successfully captured using spectral splitting method based on OFDR, thereby achieving strain demodulation for each channel. Compared with WDM WFBGAs, the maximum strain was only 1000 μϵ based on two-channel SMF.