| 摘要 |
PURPOSE: To provide a spot conversion element which is excellent in terms of insertion loss and yield of manufacture. CONSTITUTION: This spot conversion element includes an optical waveguide for propagation having a first core in which guided light of a small spot size propagates, a spot conversion optical waveguide having a second core 102a which converts the spot size of the guided light and an enlarged spot optical waveguide in which the guided light of a large spot size propagates. At least either of the thickness and width of the second core 102a of the spot conversion optical waveguide decreases gradually toward the front end of the enlarged spot waveguide and the end of the second core 102a does not arrive at the end of the enlarged spot waveguide. In addition, the enlarged spot optical waveguide is provided with a ridge structure for confining the guided light in a transverse direction. |
