| 摘要 |
PURPOSE:To enable the formation of periodic polarization inversion layers at a sufficiently large depth even in the case of production of these layers at shorter periods. CONSTITUTION:Periodic light shielding layers 3 which are opaque to UV rays or blue light are provided on a substrate 1 consisting of LiNbO3 and thereafter the substrate is heated up to a suitable temp. lower than its Curie point while the substrate is irradiated with the UV rays or blue light or after the substrate 1 is heated to the suitable temp. lower than its Curie point, the substrate is irradiated with the UV light or blue light and thereafter the substrate is rapidly cooled to turn the periodic polarization inversion layers 5. As a result, the spread by diffusion of the dopant at the time of the heat treatment like heretofore does not exist and the periodic polarization inversion layers are formed at the shorter periods and at the relatively large depth with respect to the periods. |
