Rayleigh backscattering measurement of single-mode fibers by low coherence optical time-domain reflectometer with 14 μm spatial resolution

An optical time-domain reflectometer (OTDR) with −136 dB minimum detectable reflectivity and 14 μm spatial resolution is developed based on low coherence interference. The high sensitivity was accomplished by using a high-power superluminescent diode module with a 1.5 mW fiber output and a new system configuration, both for effectively operating the balanced heterodyne detection. The reflectivity of −136 dB is only 6 dB above the shot noise limit. The first observation of 1.3 μm wavelength Rayleigh backscattering in single-mode fibers was successfully made by the OTDR with a 17 dB dynamic range and 14 μm spatial resolution.