To convert the signal light of RZ form to the signal light of NRZ form in all optical systems.
When signal light S of RZ form, with which pulse width is 25PS, and four pump beams Sp1-Sp4 of different wavelengths are inputted to a wavelength converter 101, converted signal light Sh having the same waveform as the signal light S and containing the respective wavelength component beams of the pump beams Sp1-Sp4 is outputted. When the converted signal light Sh is passed through a wavelength distributed optical fiber 102, a transmitting velocity is made different for each wavelength component beam, and converted signal light Shw of NRZ form spreading pulse width to 100PS is provided from the output terminal of the optical fiber 102. Since a light receiving device 6 receives the signal light Shw of NRZ form, a band can be narrow.
SATOU RIEKO
SUZUKI YASUHIRO
ISHIHARA NOBORU
