BRANCH LIGHT BEAM PATH CHARACTERISTIC EVALUATION SYSTEM

摘要

PURPOSE:To evaluate characteristics of individual downstream-side optical fibers at a high accuracy without any access point selection switch and any separate access point element by generating an amplification state of a Brillouin light with a signal light source and a pump light source. CONSTITUTION:Respective acoustic frequencies of downstream-side optical fibers (4-1)-(4-N) are measured beforehand. Then, a difference between a frequency (fixed) of an outgoing light (signal light) of a specified signal light source 8-i and a frequency of an outgoing light (pump light) of a pump light source 9 is controlled with a frequency controller 13 to coincide with an acoustic frequency of a specified downstream-side optical fiber 4-i desired to be evaluated. As a result, the pump light undergoes a Brillouim light amplification only within the specified downstream-side optical fiber 4-i desired to be evaluated. At this point, a waveform is observed with a photo detector 12. The waveform is analyzed with a waveform processor 14. Besides, Rayleigh scattered light and a Fresnel reflected light can be removed with a light frequency filter 11.