| 摘要 |
PURPOSE:To maintain an excellent oscillation and to attain an extremely low cost by forming a directional coupler type optical demultiplexer by using plural optical demultiplexer of the same parameter and constitution. CONSTITUTION:From light signals of wavelengths of lambda1, lambda2 incident to the input side port of a main light path 7-1, the one of lambda1 is demultiplexed by a directional coupler type optical demultiplexer 6-1, and the light transmits through a branch light path output side port 8-2. The light of lambda2 is not demultiplexed, and propagates through an output side port 7-2. A directional coupler type demultiplexer 6-2 demultiplexes the light signal of wavelength lambda1 leaked to the port 7-2-side, and lets it propagate to a branch light path output side port 9-2. Consequently, from the port output terminal 7-2, a light signal of wavelength lambda2 including no unnecessary signals can be taken out. The light signal of lambda1 demultiplexed by the demultiplexer 6-1 transmits through the light path 8-2, and demultiplexed again by a directional coupler type optical demultiplexer 6-3, and passes through an output side port 10-2. Since a mixed light signal of lambda2 propagates to the output terminal 8-2, only the light signal of lambda1 is taken out from the output terminal 10-2. |
