强激光照射下,α-LiIO3晶体中晶格振动的多模激发和模之间的相互作用

本文叙述了用调Q倍频YAG脉冲激光照射α-LiIO₃晶体,在不同的散射配置下,获得了各种散射谱图。实验表明,当用e光入射时,可以比用o光入射激发起更多不同模的晶格振动;获得了E₂模的很强的一阶、二阶斯托克斯散射线和反斯托克斯散射线,E₁模Polariton的一阶、二阶、三阶斯托克斯线和反斯托克斯线,还获得了反斯托克斯频率区一条频移为469cm^-1的新线,认为是不同模的Polariton之间的相互作用引起的。最后,提到实验中初步观察到的晶体拉曼活性的“疲劳现象”。关键词：

EXCITATION AND INTERACTION OF MULTI-MODE LATTICE VIBRATIONS IN α- LiIO3 CRYSTAL UNDER IRRADIATION OF AN INTENSE LASER

We have observed various spectra of stimulated Raman scattering (STRS) in a-LiIO₃ crystal in different scattering geometries under irradiation of an electro-optically Q-switched second harmonic YAG laser. It is shown experimentally that more multi-mode lattice vibrations .can be excited by extra-ordinary incident photons than by ordi-nary ones. We have also observed the first and second order Stokes and anti-Stokes scat-tering lines of E₁ mode, which are strong in intensity. The first, second and third order polariton Stokes and anti-Stokes lines are observed, as well as a new spectral line with a frequency shift of 496 cm^-1 in anti-Stokes frequency region, which may be attributed to interactions among polaritons with various modes.Fatigue phenomena of Raman activation for the crystal have also been indicated experimentally.