稀土材料的超快共振非线性光学特性研究

用抽运-探测技术测量光学响应材料非线性极化率的方法，研究了稀土材料非线性折射率的共振增强和超快响应的非线性动力学过程。测得钕玻璃的三阶非线性折射 率强度系数为10^-14cm^2/W，比其基质的非线性折射率强度系数提高了2个量级。用该方法研究了Nd:YVO4、Er:YAG等晶体的超快非线性响应过程。实验结果与理论分析表明，抽支-探测技术是测量非线性极化率的简单而又灵敏的方法。这一测量技术对研究与开发超高速光响应器件具有重要的实用价值。

Studies on Ultrafast Resonant Nonlinear Optics in Rare Earth Solids

Resonantly enhanced nonlinear refraction in rare earth doped solids is studied with femtosecond degenerate pump probe two beam coupling spectroscopy. An ultrafast resonant nonlinear refractive index of the order of 1×10 -14 cm 2/W is measured in Nd∶glass, and it is 10 2 times greater than the host material. It shows that both the transient probe transmission and the nonlinear refraction can be effectively controlled via the coherent coupling of probe beam with the pump through Nd∶glass sample. The experimental observation of the femtosecond resonant nonlinear refraction response in the rare earth solids may implicate important applications in ultrafast optical switching. It shows that coherent control can be applied to improve the modulation depth of ultrafast optical switching. Resonant nonlinear refraction measurements in other rare earth doped materials such as Er∶YAG and Nd∶YVO 4 demonstrate the general applicability of the pump-probe technique.