| 摘要 |
PROBLEM TO BE SOLVED: To provide a signal demodulator with proper temperature stability that can freely change a wavelength grid and the number of channels and selects the channels at high speed. SOLUTION: A photoelectric conversion mixer 11 applies heterodyne detection to an optical signal 21 that is modulated and subjected to wavelength division multiplexing, using a monochromatic light 22 that is not modulated and has a different wavelength from that of the optical signal 21, to convert the optical signal 21 into a frequency division multiplex signal 23 with a frequency equivalent to a wavelength difference between the wavelength of the optical signal 21 and the wavelength of the monochromatic light 22, a signal distributor 12 distributes the signal 23; the one distributed signal is given to a variable injection synchronous oscillator 13, which generates a locally oscillated signal 24 with a frequency equal to that of a carrier in a desired frequency channel, which is given to a base-band conversion mixer 14 with the other distributed signal, and the base-band conversion mixer 14 is homodyne detected to both to convert them into a base-band signal 25. |
