| 摘要 |
PROBLEM TO BE SOLVED: To reduce joint loss with an optical fiber without increasing manufacturing cost. SOLUTION: The tapered waveguide of an optical coupler 101 is constituted in the manner that the difference of a coupling ratio between the case of cutting the tapered waveguide at an arbitrary place and the case of cutting it at a place one step forward in the intrinsic mode with the waveguide of the same width as the cut section, becomes smaller than a value in a prescribed range. |
