| 摘要 |
PURPOSE:To facilitate optical axis adjustment and fixation and to drastically reduce coupling loss by forming a thin film optical waveguide of a waveguide for excitation which excites signal light from an optical fiber and waveguides for coupling provided in parallel to the waveguide for excitation. CONSTITUTION:The thin film optical waveguide is formed of the waveguide 7a for excitation which excites the signal light from the optical fiber 4 and the waveguides 10a and 10b for coupling which are provided in parallel to the waveguide 7a for excitation. A buffer layer 11 which is lower in refractive index than the waveguide 2 and higher than a substrate 1 is provided on the substrate 1. The refractive index difference between the waveguide 2 and buffer layer 11 is made nearly equal or smaller than that between the core and clad of the optical fiber 4 to equalize the spot size of the light intensity distribution perpendicular to the waveguide film 2 to the spot side of the optical fiber 4. The light beams excited by the waveguides for coupling is converged on one waveguide for excitation by distribution coupling. Consequently, the optical axis adjustment and fixation for the coupling between the optical fiber and thin film optical waveguide are facilitated and the coupling loss is drastically reduced. |
