| 摘要 |
PURPOSE:To obtain a waveguide type optical branching element whose loss is small and having the small wavelength dependency of a coupling ratio in a wide wavelength area, and also whose polarization dependency is mitigated. CONSTITUTION:Two directional couplers 2a, 2b are installed on the way of two optical waveguides 1a 1b arranged on a substrate 1, and the length difference DELTAL of an optical path between the optical waveguides 1a, 1b in between the directional couplers 2a, 2b is arranged, and also, a tapered optical waveguide 1c is provided on some parts of one optical waveguide, then, the wavelength and the polarization dependency of the directional couplers 2a, 2b are counterbalanced with the wavelength and the polarization dependency of the tapered optical waveguide 1c, so that the optical branching element whose loss is small and having the small wavelength dependency in a desired wavelength area can be formed as a whole. |
