To reduce the loss of signal information due to the optical nonlinear effect of an optical waveguide and to enable the optical transmission for a long distance by providing a space filter having a function which modulates the intensity and the phase of an optical signal to convert phase information of the photoelectric field to intensity information.
This circuit is provided with a light source 101 such as a DFB laser diode, a phase modulator 102, an optical fiber 103 for signal transmission, an optical circulator 104, an array waveguide grating 105, a differential filter (space filter) 106, and a photo detector 107. The differential filter 106 has intensity and phase modulation characteristics capable of converting phase information of the incident photoelectric field to intensity information. The filter 106 is brought into close contact with the focal surface of a slab waveguide approximately, and a lens may be provided on the focal surface of the slab waveguide to perform phase compensation. Incident signal light is expanded to a spectrum on the focal surface of the slab waveguide.
KUROKAWA TAKASHI
TSUDA HIROYUKI
