| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to easily change and adjust the branching ratio of an optical waveguide type directional coupler by providing the part right above the coupling part of this directional coupler with a trench part having the depth reaching a use or shallower than the same, a packing material packed in the trench part, and a heater existing above the coupling part. SOLUTION: The part right above the coupling part of the optical waveguide type directional coupler is provided with the groove (trench) 5 part of the depth reaching the core 3 or shallower than the same, the packing material 6 packed in the groove 5 part and the heater 7 existing above the coupling part. Namely, the very small groove 5 is formed in the part right above the coupling part of the optical waveguide type directional coupler and the packing material 6 is embedded therein. The refractive index of the packing material 6 is changed by such constitution, by which the same effect as the effect of actually changing the spacing between two pieces of the optical waveguides and the length of the coupled waveguides is obtd. As a result, the taking out of monitor light only during monitor and the stopping of the taking out of the monitor light when not needed are made possible. |
