Bend-Loss-Free Distributed Sensor Based on Rayleigh Backscattering in Ge-Doped-Core PCF

Abstract

We propose a bend-loss free, high-resolution, fiberoptic distributed sensor by using a new sensing fiber namely Ge-doped-core photonic crystal fiber (PCF) in optical frequency domain reflectometer (OFDR). PCF is fabricated with high concentration of Ge-doping in the small core leading to large refractive index difference between core and air-silica cladding. We achieved negligible macrobending loss in our Ge-dopedcore PCF for a bend radius of curvature down to 1 mm in experiment and the results are validated by numerical simulation. By using OFDR, with a bend radius of 1 mm, the strain and temperature sensitivities in Ge-doped-core PCF are measured to be 0.138 GHz/με and 1.46 GHz/°C, respectively, with 5 cm spatial resolution.