| 摘要 |
PROBLEM TO BE SOLVED: To improve the optical coupling efficiency irrespective of the form of optical elements and optical waveguides to be directly coupled to a ridge type optical waveguide by forming the ridge in at least one of the input or output part of the ridge-type waveguide to transfer polaritons as tapered to gradually decrease its width to the end so that the width of the ridge becomes smaller than the cut off width. SOLUTION: In the cross section of the ridge type optical waveguide,the waveguide has a core 1 in the center and has clads 2, 3 over and under the core, respectively, to form a ridge by the upper part of the core 1 and the clad 2. In this ridge type optical waveguide, the width of the ridge is decreased toward the input or output part for light. In particular, the width is gradually decreased so that the width of the ridge becomes smaller than the cutoff width. By gradually decreasing the width of the ridge to the end, the mode profile is increased and, as a result, the coupling efficiency with an optical fiber can be significantly improved. |
