| 摘要 |
PURPOSE:To obtain an optical attenuator which is free from difficulty of optical axis alignment for production and has a satisfactory vibration-proof characteristic to have a high stability, by providing two waveguides different in propagation loss formed on the surface of a substrate and a pair of optical switches which select one of these waveguides. CONSTITUTION:A waveguide 2 which is unified in one end and is branched into two twice to become four parallel waveguide parts 21-24 and is coupled twice to be unified in the other end is formed on the surface of a substrate 1. Loaded metallic films 31-34 for loss adjustment are provided on parallel waveguide parts 21-24, and the waveguide loss is different by the length of the metallic film loaded on each of parallel waveguide parts 21-24. Electrodes 4 are formed in respective Y-shaped branch parts to form Y branch type optical switches which use the electrooptic effect due to voltage application to electrodes. Either of waveguide parts is selected by the switch in each Y-shaped branch part to select one of four parallel waveguide parts 21-24. |
