Range extension in optical low coherence reflectometry achieved by using a pair of retroreflectors

The authors report an optical low coherence reflectometer (OLCR) with a distance range of 2 m. By using a pair of retroreflectors in the variable optical delay line and bouncing the local oscillator light off either moving retroreflector ten times, the distance range could be extended ten-fold from 20 cm to 2 m as compared with a conventional OLCR. The complete Rayleigh backscattering distributions of 1.53 m long silica-based waveguides were obtained by translating the retroreflector once for each waveguide. The measurement error of the loss coefficients was ±0.0025 dB/cm