High spatial resolution distributed transverse-load sensing based on polarization-sensitive optical frequency domain reflectometry.

We proposed and demonstrated a high spatial resolution distributed transverse-load (TL) sensor based on polarization-sensitive optical frequency domain reflectometry (P-OFDR) using a polarization-maintaining photonic crystal fiber (PM-PCF). The fiber exhibits high TL sensitivity because of the asymmetric air hole structure in its cladding, which changes the local birefringence through the photoelastic effect of the fiber. The dependence of birefringence on TL is investigated through theoretical simulation. Distributed TL sensing with a high spatial resolution of 2.51 cm is demonstrated, where the TL responses of the two orthogonal polarization states are measured by the P-OFDR system, respectively. The slow-axis and fast-axis signals show strong anisotropy. Under slow-axis TL, the sensitivities are 1.3014 GHz/N and -0.2018 GHz/N for the slow and fast axes, respectively; under fast-axis TL, they are -0.1363 GHz/N and 0.8473 GHz/N, respectively.