Abstract
The authors report a signal-to-noise ratio (SNR) improvement in the Rayleigh backscattering measurement of a silica-based waveguide over 20 cm, achieved by constructing a complex optical low coherence reflectometer with an auxiliary interferometer. The best SNR achieved is 38, which corresponds to signal fluctuations of ±0.1 dB, and the spatial resolution is 1.3 cm. The measured Rayleigh backscattering distribution clearly revealed the waveguide loss.