| 摘要 |
PURPOSE:To enhance coupling efficiency and to miniaturize the above optical coupler by working a thin film or optical waveguide layer constituting a diffraction grating to a specific shape and changing the coefft. of coupling according to places. CONSTITUTION:The thin film 3 is laminated by gradually changing the thickness thereof in the propagating direction of the guided light in the optical waveguide layer and in succession, the thin film 3 is removed until the optical waveguide layer 2 is exposed, by which the groove width in the propagation direction of the respective grooves dug in the thin film 3 is so formed as to have the same length without depending upon the places. The height in the thin film patterns for each of the respective pitches in the thin-film patterns is successive ly changed in the propagation direction. The coefft. of coupling of the diffraction grating optical coupler is, therefore, changed along the propagation direction. The small-sized diffraction grating optical coupler which can make the light having an ordinary intensity distribution incident on the inside of the optical waveguide with good efficiency is obtd. in this way. |
