| 摘要 |
A separation structure for selecting the propagation mode of the light waves in a light wave guide, the latter being constituted by a strip (100) of a semiconductor material having a first refractive index formed on a semiconductor substrate (10) of a material having a second refractive index lower than the first index and such that the light is confined in the strip forming the guide. The structure is arranged in the path of the light beam in such a manner that it de-limits in the guide on the one hand at least one region (G1), in which the propagation of the light wave is monomode, and on the other hand a region (G11), in which the propagation is bimode. According to the invention the said separation structure is formed by an abrupt variation of the dimension of the guide perpendicular to the substrate, the flat surface of the substrate being chosen as reference for the measurement of this dimension in such a manner that, by defining e1 as the dimension of the guide perpendicular to the substrate in the monomode region and e2 as its dimension in the bimode region, these dimensions are associated by the relation <IMAGE> in which lambda is the transported wavelength, ng is the refractive index of the light wave guide (100) and nS is the refractive index of the substrate (10). |
