不同激光脉冲作用下ZnS晶体非线性光学特性

用Z-scan技术在532 nm的皮秒激光脉冲和800 nm飞秒激光脉冲作用下分别研究了ZnS晶体的非线性吸收及非线性折射特性。实验结果表明,ZnS晶体在532 nm的皮秒激光脉冲作用下非线性吸收为双光子吸收,其非线性吸收系数为5.310-11 m/W,在800 nm的飞秒激光脉冲作用下非线性吸收为三光子吸收,非线性吸收系数为0.5910-21 m2/W2;在532 nm皮秒激光脉冲作用下,ZnS晶体的非线性折射率符号为负,自由载流子产生的非线性折射率的改变占主导,而800 nm飞秒激光脉冲作用下,ZnS晶体的非线性折射率符号为正,束缚电子产生的非线性折射率的改变为主要因素。

Nonlinear optical properties of ZnS with different laser pulse

Based on Z-scan technique, the nonlinear absorption and nonlinear refraction characteristics of ZnS crystal were researched in the case of wavelength of 532 nm picosecond laser pulses and wavelength of 800 nm femtosecond laser pulses. Experimental results are as follows. The absorption of ZnS crystal is two-photon absorption and the nonlinear absorption coefficient is 5.310-11 m/W in the case of wavelength of 532 nm picosecond laser pulses. The absorption of ZnS crystal is three-photon absorption and the nonlinear absorption coefficient is 0.5910-21 m2/W2 in the case of wavelength of 800 nm femtosecond laser pulses. Under the effect of 532 nm picosecond laser pulses, the nonlinear refractive index sign of ZnS crystal is negative and the change of nonlinear index of refraction generated by free carrier is the dominant factor. But under the effect of 800 nm femtosecond laser pulses, the nonlinear refractive index sign of ZnS crystal is positive and dominant factor is the change of nonlinear index of refraction generated by bound electron.