Measurement of Rayleigh backscattering in single-mode fibers based on coherent OFDR employing a DFB laser diode

Rayleigh backscattering in a single-mode optical fiber was measured by coherent optical frequency-domain reflectometry (C-OFDR) employing a frequency-variable distributed-feedback laser diode (DFB-LD). Backscattered power from the neighborhood of the far end of a 0.5-km-long fiber was measured with a spatial resolution of 50 cm. The insertion of a delay line fiber in the reference optical path and an acoustooptic frequency shifter in the signal optical path made it possible to measure backscattering in a long optical fiber in spite of the short coherence length of the DFB-LD.<
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