摘要
利用Z-scan方法系统地研究了(NBu4)2[Zn(dmit)2]在丙酮溶液中的共振和非共振三阶非线性光学特性和光限幅特性.在532nm皮秒脉冲激光的激发下,样品表现了较强的饱和吸收特性,三阶非线性折射率为负值;在1064nm皮秒脉冲激光激发下样品三阶非线性折射率为正值,并表现出了明显的光限幅效应.样品的三阶非线性吸收系数β=-2.94cm/GW.估算了共振条件下的共振增强因子约为32.2,由此推断:由于共振增强的影响,在相同实验条件下,由532nm的激光激发比在1064nm激发下样品的三阶非线性极化率大两个数量级.在λ=1064nm和532nm两种波长的激发下样品的分子二阶超极化率γ分别等于1.18×10-32(esu)和-3.77×10-30(esu).
We have reported a study on the non-resonant and resonant third-order nonlinear optical response of a charge transfer salt（ NBu4 ）2 [Zn（dmit） 2] （ dmit= 2-thioxo-1,3-dithiole-4,5-dithiolate） with fundamental frequency 1 061 nm and doubled-frequency 532 nm picosecond pulses . Under 532 nm excitation, the solution exhibits strong saturable absorplion （SA） and negative third-order nonlinear refractive index attributed to self-defocusing contrary to that under 1 064 nm excitation： and the nonlinear absorption coefficient β=-2.94 cm/GW. The resonance factor was calculated as 32.2, the third-order nonlinear refractive index in the same conditions enlarge 10^2 compared with that under 1 064 nm excitation. The molecular second hyperpolarizability γ（esu） at λ= 1 064 nm and 532 nm is 1.18 × 10^-32 and - 3.77 × 10^-20, which are obtained from the experimental calculated results, respectively. And the sample reveals large optical limiting effect under 1 064 nm excitation.
出处
《河南大学学报（自然科学版）》
CAS
北大核心
2009年第2期134-138,共5页
Journal of Henan University:Natural Science
基金
河南省教育厅自然科学基金资助项目(2006140001)
河南大学自然科学基金重点项目(04ZDZR002)
关键词
Z扫描
三阶非线性
分子二阶超极化率
共振因子
光限幅
Z- scan
third-order nonlinear ： molecular second hyperpolarizability
resonant factor
optical limiting
