| 摘要 |
PURPOSE:To obtain the optical multiplexer/demultiplexer which is efficient by making light beams which differ in wavelength incident on an optical waveguide, where a diffraction grating is arranged between two mode index type lenses which are achromatic lenses, from optical fibers. CONSTITUTION:The optical waveguide 8 which has the transmission type diffraction grating 11 between the two mode index type lenses 9 and 10 is arranged on a substrate across a buffer layer 7. The mode index type lenses 9 and 10 have their film thicknesses and refractive indexes set so as to serve as the achromatic lenses almost at designed wavelength. Projection light beams from four optical fibers from light sources lambda1-lambda4 at one end of the optical waveguide 8 of an optical waveguide element 12 like this are converged, diffracted, and converged through the optical system consisting of the lens 10, diffraction grating 11, and made incident on one optical waveguide 15 at the other end. Further, the traveling direction of light is inverted and light from one optical waveguide 14 is demultiplexed by wavelengths. Consequently, three-dimensional precise machining is not necessary and the optical multiplexer/demultiplexer which has good optical coupling efficiency is obtained. |
