| 摘要 |
PURPOSE:To obtain excellent isolation even any kind of connection means is connected to an emission port by adopting the constitution such that a path of a prescribed coupling coefficient is caused at least twice between paths of the 1st incident port and the 4th incident port. CONSTITUTION:The coupler consists of wavelength demultiplexing/multiplexing coupler sections 11-14, when a light including wavelengths lambda1, lambda2 is made incident into a port 1, most of the light in the wavelength lambda1 is emitted to a port 2 and most of the light in the wavelength lambda2 is emitted to a port 3 and only a little light is emitted to other ports. A path reaching the incident port 4 by the reflection in the emission ports 2, 3 when the light in the wavelength lambda2 is emitted to the incident port has a very small isolation because the relation of C2<<1 and C3 1 exists in prescribed coupling coefficients C2, C3. Thus, the isolation is improved even if any kind of the connection means is in use. |
