| 摘要 |
PURPOSE:To reduce the wavelength dependency and to improve the wavelength characteristic by constituting the device so that between split waveguides being adjacent to each other, a code of a propagation constant difference between two pieces of partial waveguides for constituting its split waveguides is inverted. CONSTITUTION:On a silicon substrate 11, the lower clad layer 12 of 20mum thick, a core layer 13 of 2mum thick, and the upper clad layer 14 of 1.5mum thick are formed successively by quartz, and also, waveguides 1, 2 are formed like a ridge at an interval of 7.2mum thereon. In this case, as for the waveguides 1, 2, in both of them, road width is varied in an intermediate position of the whole, its cross sectional structure is varied, two equally split conductive wave paths A, B are formed, and also, between the split waveguides being adjacent to each other, a code of a mutual propagation constant difference is inverted. In such a way, the wavelength characteristic becomes flat, and the wavelength dependency becomes small. |
