用Z扫描技术研究Pd(mpo)2的非线性光学特性

为了研究一种新型功能配合物材料Pd(mpo)2的非线性光学特性,把二甲基甲酰苯胺(DMF)溶剂稀释的Pd(mpo)2溶液(浓度为0.75×10-4mol/L)作为待测样品,采用脉冲宽度为7ns,波长为532nm的激光束,对该样品进行了Z-扫描实验,测量了Pd(mpo)2材料的非线性吸收和非线性折射系数。实验发现,当入射光强很小时,其非线性吸收系数β=(1.916±0.016)cm/Gw,非线性折射系数γ0=-(3.153±0.048)×10-5cm2/Gw,且β和|γ|随入射光强的增大而线性减少。合理地解释了Pd(mpo)2的非线性光学特性产生机理:非线性吸收来自于近共振双光子吸收,而非线性折射是由于近共振双光子吸收造成的折射加强。非线性吸收和非线性折射系数随光强的增大而线性减少是近共振双光子吸收引起粒子数重新布居的结果。

Study on Optical Nonlinearities in Pd(mpo)2 by Z-Scan Technique

Pd(mpo)2 complex is a kind of new functional coordination compound. In order to study the optical nonlinearities of this material, the nonlinear optical absorption and refraction coefficients of Pd(mpo)2 complex were measured by using the Z-scan technique. In the Z-scan measurement, the 7 ns laser pulses at 532 nm wavelength were delivered. The sample is the dimethylformanide (DMF) solution of Pd(mpo)2 with the concentration of 0.75×10-4 mol/L. The results show that the nonlinear absorption coefficient β0=(1.916±0.016) cm/GW and nonlinear refraction coefficient γ0=-(3.153±0.048)×10-5 cm2/GW when incident irradiance is very low, and the nonlinear absorption and refraction coefficients linearly decrease with the irradiance increasing. The nonlinear absorption originates from the near resonant two-photon absorption while the nonlinear refraction is enhanced by near resonant two-photon absorption. The linear dependences of the optical nonlinearities on the incident irradiance arise from the population redistribution due to the near resonant two-photon absorption.