| 摘要 |
PURPOSE:To realize bidirectional light coherent communication with simple constitution and in which a few amount of noise or interference exists, by constituting a device in such a way that one side of the input waveguides of second and third directional couplers having the same structure as that of a first directional coupler is connected to the output waveguide of the first directional coupler in which two waveguides are arranged in parallel. CONSTITUTION:Optical signals of wavelength lambda1 and lambda2 are made incident on the waveguide 15. The optical signal of wavelength lambda1 passes through the directional couplers 1-1 and 1-2, and passe a beam splitter 8-1, and is made incident on a light receiving element APD4. On the light receiving element 4, an optical signal 10-2 that is a part of a semiconductor light receiving element LD3 which oscillates with wavelength lambda2, is reflected by the beam splitters 8-2 and 8-1 and made incident, and the reception of optical heterodyne detection is performed by the optical signal 11 of wavelength 1, and the optical signal 10-2 of wavelength lambda2. The remaining optical signal of a semiconductor light emitting element 3 which oscillates with the wavelength lambda2 passes the beam splitter 8-2, and is inputted to an optical modulator MOD7, and external modulation is applied at the modulator, and an optical signal 10-1, after wave-guiding the directional couplers 1-3 and 1-1, advances the waveguide 16, and is propagated though an optical fiber, and is transmitted to a station on a down side. |
