| 摘要 |
PURPOSE:To couple an optical semiconductor element and an optical function element with a small loss in a small-sized constitution by making the spot diameter of the optical wave, which is transmitted in an input/output optical waveguide, smaller than that of the optical wave which is transmitted in a waveguide having an optical processing function. CONSTITUTION:The refractive index on a sectional part 18 of an input/output optical waveguide 16 has distribution shown in a figure A in the direction perpendicular to the optical axis of the waveguide, and its maximum refractive index is nS+DELTAn1 where nS is the refractive index of the substrate. Meanwhile, the refractive index on a sectional part 19 of a waveguide 5 having the optical processing function has distribution shown in a figure B, and its maximum refractive index is nS+DELTAn2, and DELTAn1>DELTAn2 is true. A connection part 17 between waveguides 16 and 5 is so formed that the refractive index is gradually changed from the distribution shown in the figure A to that shown in the figure B for the purpose of reducing the loss due to mode conversion of a guided light. Since the refractive index DELTAn1 of the waveguide 16 is higher than the refractive index DELTAn2 of the waveguide 5, the waveguide 16 has a stronger light shutting effect than the waveguide 5, and the diameter of the light spot in the waveguide 16 is smaller than that in the waveguide 5. |
