| 摘要 |
PURPOSE:To stop down a wavelength converted wave into a small spot by selecting the clad material and core diameter of the light wavelength converting element formed by charging a core made of a nonlinear optical material in a clad which has a lower refractive index. CONSTITUTION:The light wavelength converting element 3 where the core 1 made of the nonlinear optical is arranged in the clad 2 having the lower refractive index converts a basic wave 5 guided in the core 1 into a 2nd higher harmonic 5' and its conic wave front is converted into a plane wave front by a conical clad end surface 2a. The clad material and core diameter of the light wavelength converting element 3 are so selected that wavelength depen dency characteristics deltathetao/deltalambda and deltan/deltalambda of a phase matching angle thetao and a refractive index (n) are in relation shown by an expression I and the difference between the left member and right member of this expression is within a range less than Sin<-1>(lambda/2Dn), where lambda and D are the wavelength and phase matching angle of the wavelength-converted wave, (n) is the refractive index of the clad to the wavelength-converted wave, and thetao is the phase matching angle. |
