To obtain an full light processing type light frequency tracking device, in which the frequency interval wanted to be set is not limited by the band of an electric circuit, by providing a wavelength converter having specific functions.
First wavelength converter to n-th wavelength conveter respectively performing wavelength conversions two times are cascaded. A first four- wave mixture generating means 13-1 performs the wavelength conversion of an input signal light beam by a four-wave mixture with a first reference light beam. Here, the light frequency of the first reference light beam is set so that light beams are arranged in the order of the input signal light beam, the first reference light beam and a first wavelength converted light beam (an intermediate output light beam). A second four-wave mixture generating means 13-2 performs the wavelength conversion of the intermediate output light beam by a four-wave mixture with the intermediate output light beam and a second reference light beam. Here, the light frequency of the second reference light beam is set so that light beams are arranged in the order of the intermediate output light beam, the second reference light beam and a second wavelength converted light beam (an output light beam).
KATAOKA TOMOYOSHI
HAGIMOTO KAZUO
