| 摘要 |
PURPOSE:To obtain such a stable wavelength converting element that secondary higher harmonic generating SHG output light has no wave front aberration by providing a channel optical waveguide which has a light propagation axis in the direction of the period of self-polarization on the surface of a Z-cut lithium niobate crystal plate. CONSTITUTION:The channel optical waveguide 3 which has the light propagation axis in the direction of the period of self-polarization is provided on the surface of the Z-cut lithium niobate crystal plate 1 which has the period of alternately inverted self-polarization along the surface. The period LAMBDA of the alternately polarized self-polarization is so determined that beta<(2omega)>-2beta<(2w)>=2theta/LAMBDA, where beta<(omega)> is the wave number for the basic wave (frequency omega) of the channel optical waveguide 3 and beta<(2omega)> is the wave number of the channel optical waveguide 3 for the secondary higher harmonic of the basic wave. Then the basic wave is applied to the channel optical waveguide 3 from one end and the secondary higher harmonic is obtained from the other end. Consequently, the waveguide type wavelength converting element which is free from wave front aberration in SHG output light is obtained. |
