Optical signal demodulator, optical signal demodulating method, and optical add-drop multiplexer

An optical signal demodulator, comprising:

• a detecting unit configured to detect an intensity of transmitted light obtained by an optical signal generated by a second signal being superimposed on a first signal using frequency modulation, transmitting a wavelength-variable filter;
• an obtaining unit configured to obtain a spectrum of the optical signal using the wavelength-variable filter of which the transmitted wavelength band has been swept;
• an identifying unit configured to identify a peak wavelength which is a wavelength corresponding to a peak position of the spectrum;
• and
• a demodulating unit configured to demodulate the second signal based on an intensity of a specific wavelength that has been set with the peak wavelength of the intensity detected by the detecting unit according to the sweep processing as a reference.

An optical add-drop multiplexer, comprising:

• an obtaining unit configured to obtain a spectrum of an optical signal generated by a second signal being superimposed on a first signal using frequency modulation;
• an identifying unit configured to identify a peak wavelength which is a wavelength corresponding to a peak position of the spectrum;
• and
• a demodulating unit configured to demodulate the second signal from the optical signal using a wavelength-variable filter to which a transmitted wavelength band has been set based on the peak wavelength.

An optical signal demodulating method, comprising:

• obtaining a spectrum of an optical signal generated by a second signal being superimposed on a first signal using frequency modulation;
• identifying a peak wavelength which is a wavelength corresponding to a peak position of the spectrum;
• and
• demodulating the second signal from the optical signal using a wavelength-variable filter to which a transmitted wavelength band has been set based on the peak wavelength.

An optical signal demodulator, comprising:

• memory;
• and
• a processor;
• wherein the processor configured to:
• obtain a spectrum of an optical signal generated by a second signal being superimposed on a first signal using frequency modulation,
• to determine a peak wavelength which is a wavelength corresponding to a peak position of the spectrum, and
• to demodulate the second signal from the optical signal using a wavelength-variable filter to which a transmitted wavelength band has been set based on the peak wavelength.