| 摘要 |
PURPOSE:To improve the reliability and to reduce the loss and to miniaturize the optical demultiplexing circuit, by coupling plural linear waveguides for input and output with plural optical waveguide circuits for wavelength separation. CONSTITUTION:A directional coupler 13 demultiplexes only monitor light be tween signal light and the monitor light which are both made incident on a main waveguide 2, couples it with a loop-back waveguide 4 being a 3rd optical waveguide. The directional coupler 14 couples the monitor light which is guided by the loop-back waveguide 4 with the main waveguide 3. The monitor light is therefore demultiplexed from a 1st optical waveguide 2 to a 3rd optical waveguide 4, then coupled with a 2nd optical waveguide 3, and projected from the input port of the 2nd optical waveguide 3. The signal light, on the other hand, is propagated in the 1st optical waveguide from one port to the other port. Consequently, the reliability, productivity, size and weight reduction are improved. |
