| 摘要 |
PURPOSE: To provide a waveguide having equivalent refractive index with good reproducibility and prevented from diffusion of Li to outside by annealing a crystal in a wafer state and then lapping, polishing and thermally diffusing metal. CONSTITUTION: After a grown crystal is sliced, the crystal wafer is heat treated (annealed) in an atmosphere to obtain a desired absorption coefft., and subjected to lapping and polishing. Thus, the obtd. crystal wafer shows no variation in the absorption coefft. Then the crystal wafer is subjected to thermal diffusion of metal. Or, a crystal wafer having a same or lower absorption coefft. than the crystal wafer after thermal diffusion is used as the crystal wafer before thermal diffusion of metal. The absorption coefft. is obtd. from the IR transmittance at 2.87mm wavelength. The absorption coefft. represents the proton density in the crystal. Thereby, an optical waveguide having a same equivalent refractive index and a mode can be produced in every production. |
