Études par spectroscopie Raman polarisée des effets photoélectrostrictifs dans LiNbO3 photoréfractif

摘要

Lithium Niobate is an optical material used in many applications in optoelectronics through its electro-optical, piezoelectric and quite exceptional nonlinear optical properties. Among these properties and applications, the photorefractive effect has created numerous studies. This effect depends on the nature and the concentration of dopant; in particular by doping with Fe ions is known to increase the photorefractive efficiency. It is therefore important to know and to manage the structure of the material during Fe doping.The aim of the thesis is to study Raman spectra changes generated by the photorefractive effect.Our results show that the photorefractivity is manifested by different effects:• A mechanical deformation of the crystal lattice, causing a displacement of some Raman lines• The defocusing of the laser beam disrupting its propagation in the material, and thus changes in the Raman spectrum• Nonlinear effects of polarization manifested by activating of forbidden Raman lines.