| 摘要 |
PURPOSE:To reduce insertion losses by using diffraction gratings of less number of grooves by installing one or more diffraction gratings on the surfaces of a homogeneous transparent body, and so arranging these that an incident light beam receives wavelength dispersion plural times by the diffraction gratings. CONSTITUTION:Two sets of parallel opposite surfaces 11-14 are formed to a homogeneous transparent body 1, and diffraction gratings 21, 22 are adhered and fixed to the surfaces 11, 12 and near parabolic rod lenses 31, 32 to the surfaces 13, 14. Further, an incident optical fiber 40 as an optical transmission element is fixed to the lens 31, and optical fibers 51-60 as photodetectors are fixed to the lens 32. An input optical beam 61 is diffracted plural times by the diffraction gratings 21, 22 and are wavelength dispersed, so that the beams are coupled by each wavelength to the fibers 51-60. Hence, the wavelength spaces between channels are made small and insertion losses are decreased by using the diffraction gratings of less number of grooves which are high in diffraction efficiency and are obtainable relatively easily. |
