DEVICE AND METHOD OF MONITORING POLARIZATION SCRAMBLER, AND OPTICAL TRANSMISSION DEVICE

PROBLEM TO BE SOLVED: To detect (monitor) an operation state of a polarization scrambler in a simple manner.SOLUTION: A device of monitoring a polarization scrambler has: a polarization passing device 14 that passes light with specific polarization among output light of the polarization scrambler; a photoelectric converter 15 generating an electric signal depending on a receiving intensity of light that has passed through the polarization passing device 14; and a detector 16 detecting from the electric signal a modulation component depending on a frequency of a polarization control signal. The detector 16 has: a wavelength filter 161 passing signals of components in a predetermined band among frequency components included in the electric signal; and an amplifier circuit 163 detecting from the signal a signal having the same frequency component as a modulation frequency signal that is given to the polarization scrambler by a polarization controller to detect the modulation component from an output from the wavelength filter.