| 摘要 |
PURPOSE:To produce the flush type optical waveguide having high coupling efficiency to an optical transmission medium having a mode field shape by once diffusing a metal element into an LiNbO3 substrate, then forming an LiNbO3 layer on the substrate and executing the rediffusion treatment of the metal element. CONSTITUTION:The fresh LiNbO3 layer 4 is formed to cover the Ti-diffused region 2a and is again held for about 3 hours at 1,050 deg.C, by which the Ti forming the Ti-diffused region 2a is further diffused. The Ti diffuses further into the LiNbO3 substrate 1 and similarly diffuses into the LiNbO3 layer 4 as well, thereby forming the Ti-diffused region 2a'. The diffusion distribution over the entire part of the Ti-diffused regions 2a and 2a', therefore, approximates the symmetrical shape in the depth direction of the substrate. The efficient coupling to the single-mode optical fiber, etc., having the mode field shape in the respective directions is executed in this way. |
