| 摘要 |
PURPOSE:To prevent deterioration of a waveguide type SHG element by heat generation thereof and to prevent degradation in the efficiency by providing the waveguide type SHG element freshly with a third layer for higher efficiency and clad protection on the outside of the element. CONSTITUTION:A glass fiber consisting of two layers of a core 1 and a clad 2, is provided with a metallic thin film 3 as the third layer. Basic wave 5 coupled to the inside of the core 1 are confined and propagated in the core 1 having a high refractive index. Second higher harmonics 4 generated by the interaction with the nonlinear material of the core 1 are radiated into the clad 2 at a certain angle determined by the respective refractive indices of the core 1 and the clad 2. The radiated second higher harmonics progress while repeating total reflection at the boundary of the clad 2 and the metallic thin film 3 and are efficiently taken out of an exit end face without attenuation by scattering or absorbing, etc. As a result, the propagation loss by scattering and absorbing by the adhered matter and deposit at the boundary face between the clad layer and the air layer is prevented. |
