OPTICAL TRANSMISSION MONITORING AND OPTICAL TRANSMISSION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an optical transmission monitor of a simple configuration that identifies a cause of strength fluctuations in multi-wavelength signal light. SOLUTION: Part of light received by an optical transmission monitor 31 is extracted by an optical branching element 311 and detected by a photodetector 313. The light received by the photodetector 313 includes ASE noise light in addition to 8 wavelength signals λ1-λ8. Furthermore, part of the light received by the optical transmission monitor 31 is extracted by an optical branching element 312 and light of a wavelength band including 4 sets of wavelength λ5-λ8 passes through an optical fiber grating 314 and detected by a detector 315. The light at the optical wavelength band received by the photodetector 315 includes ASE noise light at a signal light wavelength band in addition to the signal light with 4 wavelength sets λ5-λ8. A monitor section 316 compares a rate of change in the strength of light detected by the photo detectors 313, 315 respectively and monitors light transmission based on the result of comparison.