| 摘要 |
PROBLEM TO BE SOLVED: To provide the optical waveguide input/output device of high input /output light coupling efficiency provided with the grating coupler of wide- grating width and grating interval. SOLUTION: This device 1 is constituted of a substrate 2, an optical buffer layer 3, an optical waveguide layer 4 and the grating coupler 10, etc. When q-th order diffracted light beams are input/output light coupled by the grating coupler 10, at the time of defining the effective refractive index of the optical waveguide layer 4 as N, the refractive index of the optical buffer layer 3 in contact with the optical waveguide layer 4 as nb , the refractive index of air in contact with the optical waveguide layer 4 as nc and the wavelength in a free space of light asλ, the grating pitchΛand duty factor (a) of the grating coupler 10 satisfy the three conditional formulas of a (q+1)=m (m=±1,±2,±3...),|N+(q+2)λ/Λt}/nb|>1 and|(N+gλ/Λ/nc|<1. |
