Experiment Research for the Influence of Polarization Direction of Low-power Near-infrared Light on the Light-induced Refractive Index Change
低功率近红外光的偏振方向对光致折射率变化影响的实验研究

The influence of the polarization direction of light-induced refractive index change(Δn) induced by light irradiation in In:Fe:LiNbO3 crystals were investigated by using ordinary and extraordinary recording polarization(opol/epol) laser beams of low-power near infrared light.The experimental results show that the curves are similar of the refractive index distribution,but they have opposite signs,and a further difference is that the saturation refractive index change is clearly larger for ordinary recording polarization,changing to extraordinary recording polarization result only about one-third.The refractive index change in photorefractive crystals induced by two polarization directions of near infrared light is differ from visible light.The crystal illuminated with extraordinary polarized light in the middle of the irradiation region,one can see a strong increased of the refractive index.Moreover,the results can be very useful for fabrication of tailored nonlinear optical device with different refractive index distributions by changing different the polarization directions of near infrared beam.