Detection of faults in short fiber by the phase compensated reflectometer

The authors describe an optical frequency-domain reflectometer (OFDR) which is designed on the basis of the phase compensation technique. The instrument can locate Fresnel reflection points in a short-range fiber (from 0.5 m to 2 km) with ±0.1-m accuracy, and it has 0.3-m spatial resolution with an 800-MHz swept bandwidth. Using the PCR (phase-compensated reflectometer), multiple Fresnel reflections in short fibers have been accurately measured with SNR (signal-to-noise ratio) from 35 to 10 dB. The PCR is thus suitable for locating faults in a short fiber. In addition, this reflectometer will be able to measure closely spaced reflections in a long fiber by narrowing the bandwidth of an IF (intermediate frequency) signal receiver and increasing the optical power