| 摘要 |
PROBLEM TO BE SOLVED: To optically couple a bulk type optical element, an optical fiber, an optical active element such as a semiconductor laser and other waveguide type parts simply with a low loss by specifying a gap width by a specified inequality. SOLUTION: An optical waveguide K2 is provided with one and more gap parts in which an optical element is packaged in the direction crossing a waveguide core 2 between a light entrance end part 2a and a light exit end part 2b. The gap width G of the gap part satisfys G<0.32πnω<2> /λ, where,λ: the wavelength of a waveguide length, n: refractive index of optical element,ω: the mode field radius of waveguide light. Otherwise, at least one of the gap parts satisfys 0.975<(1+((λG)/(2πnω<2> ))<2> )<-1> , where,λ: the wavelength of a waveguide length, G: gap width, n: the refractive index of the gap part,ω: the mode field radius of waveguide light. By arranging plural gap parts, the coupling loss is suitably decreased compared with the case that one gap width equal to the sum of the plural gap widths is provided. |
