| 摘要 |
An optical path routing element includes first and second optical waveguide that are parallel to each other. The first and second waveguides have the same thickness and have the same width, the width being larger than the thickness. The width is within a range based upon coupling lengths of the first and second waveguides for a TE polarization and for a TM polarization such that the difference between the coupling length for TE polarization and the coupling length for TM polarization is no more than a predetermined percentage times the sum of the coupling length for TE polarization and the coupling length for TM polarization divided by 2. |
