| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical device which executes the control of signal light at a low cost. SOLUTION: An optical waveguide is formed on a substrate consisting of quartz glass as a base material to provide the substrate with a directional coupler 25 of which the coupling length 1 to be evanescently coupled is half the complete coupling length Lc. The terminal of the coupling length is contiguous with the end face of the substrate 20. A total reflection film 20 is arranged to face the waveguide end faces. Electrodes 27, 28 for controlling are formed right above the first and second optical waveguides 21, 22 forming the directional coupler 25 or at the peripheries thereof and are locally heated, by which the refractive index (n) of the optical waveguides of the directional coupler 25 is changed. As a result, the complete coupling length Lc may be changed and, therefore, the energy distribution ratio of the exit light outputted from the directional coupler 25 may be changed. |
