| 摘要 |
PURPOSE:To make wave-guided light incident on a diffraction grating with high accuracy so that high diffraction efficiency can be obtained, by installing markers which are provided in prescribed positional relations with the diffraction grating or diffracting period structure producing means to the surface of an optical waveguide. CONSTITUTION:A parallel laser luminous flux 28 from a light source is made incident on an optical waveguide 21 after it is converged in the direction normal to the surface of an optical waveguide 21 by means of a cylindrical lens 31. A pair of markers 29 and 30 are provided on the surface of the optical waveguide 21 in corresponding to the incident end face. Namely, the luminous flux reaches a diffraction grating 26 after it becomes wave-guided light 32 and only the component of 0.84mum wavelength is Bragg diffracted. The transmitted wave-guided light then reaches another diffraction grating 27, where only the 1.3mum component of the wave-guided light is Bragg diffracted and the other component is transmitted. The diffracted rays of light 33 and 34 are respectively led to photodetector sections. When a luminous flux is made incident in the direction normal to the line connecting the markers 29 and 30 with each other, the Bragg diffraction conditions are satisfied to the diffraction gratings 26 and 27. |
