OPTICAL TRANSMISSION MONITOR AND OPTICAL TRANSMISSION MONITOR SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an optical transmission monitor and an optical transmission monitor system that can monitor signal light with an inexpensive configuration. SOLUTION: In the optical transmission monitor, a photocoupler 111 branches signal light that is wavelength multiplexed and sent through an optical transmission line 10. A photodetector 131 detects the light, a photocoupler 112 branches the signal light and photodetector 132 detects the light via an optical filter 120. The optical filter 120 has a wavelength dependence with a constant loss for the signal line wavelength band. A monitor section 140 receives all signal light intensity detected by the photodetectors 131, 132 and discriminates on which of span loss fluctuation and wave number fluctuation the signal light level fluctuation depends on the basis of the relation of the intensity.