钴卟啉溶液的光限幅特性研究

对大分子有机化合物钴卟啉的非线性光学特性在 4 5 7 9,4 88和 5 14 5nm三个连续激光波长下进行了研究。用单光束z scan技术测到三个曲线均是先出现峰值后出现谷值 ,按照Sheik bahae等人的理论该样品的非线性折射率为负值 ,即样品具有热自散焦效应。反饱和吸收特性的研究结果得到三个透射率T随入射激光功率的增大而减小的曲线 ,表明该样品在这三个波长下均呈现出反饱和吸收效应。众所周知 ,热自散焦效应和反饱和吸收效应都能导致光限幅。文章的实验结果也表明 :钴卟啉在三个波长下均具有光限幅特性 ,限幅阈值随着波长的减小而减小 ;其光学限幅效果好且限幅阈值低 ,是一种有较大潜在应用价值的新型光限幅材料。因此 ,可以利用这两种效应对钴卟啉的共同作用 ,制成新型光限幅器件

Investigation on Optical Limiting Performance in Solution of Cobalt Porphyrin

The nonlinear optical effects of cobalt porphyrin have been investigated with three CW laser lines of 457.9, 488 and 514.5 nm, respectively. Three curves with peak followed by valley using the single beam z-scan technique were obtained. According to M Sheik-bahae's theory the sample has a negative nonlinear refractive index, that is, there is a thermal self-defocusing effect. Three curves of transmittance show a decrease with the increase in the incident laser power, which means that the sample has reverse saturated absorption property under the three laser wavelengths. It's well known that both thermal self-defocusing effect and reverse saturated absorption can lead to optical limiting. It was found that cobalt porphyrin has the optical limiting effect under those wavelengths, and that the critical value of optical limiting decreases with the decrease in laser wavelength. Furthermore, the effect of optical limiting is very good and the critical value is very low, so it's a new optical limiting material with a great potential application value. For that, it is possible to use the co-operation of both effects from cobalt porphyrin to produce a new kind of optical limiting device.