CHARACTERISTIC ANALYZER FOR OPTICAL FIBER LINE AND CHARACTERISTIC ANALYSIS METHOD THEREOF

摘要

PROBLEM TO BE SOLVED: To achieve the reduction of measurement time about an optical fiber strain variation of an optical fiber line in a lengthwise direction of the optical fiber line.SOLUTION: Measurement in a short time can be achieved by allowing a Brillouin gain spectrum at a point on an optical fiber line to be obtained in a single measurement. Concretely, the Brillouin gain spectrum is obtained by counter propagation of a probe light pulse train including X probe light beams different by frequencies and a pump light pulse train including X pump light beams different by frequencies, which pair with the probe light beams. A frequency difference of an i-th probe-pump pair (pair of a probe light beam and a pump light beam) is changed from that of an (i-1)th probe-pump pair byΔf, and the Brillouin gain spectrum is obtained from Brillouin gains of respective probe light beams obtained by this change of frequency differences.