Saturable and reverse saturable absorption and nonlinear refraction in nanoclustered Amido Black dye–polymer films under low power continuous wave He–Ne laser light excitation
Saturable and reverse saturable absorption and nonlinear refraction in nanoclustered Amido Black dye–polymer films under low power continuous wave He–Ne laser light excitation
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DOI：
10.1088/1464-4258/11/12/125204
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发表时间：
2009-12
影响因子：
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通讯作者：
G. Sreekumar;P. G. L. Frobel;C. I. Muneera;K. Sathiyamoorthy;C. Vijayan;Chandrachur Mukherjee
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文献类型：
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作者：
G. Sreekumar;P. G. L. Frobel;C. I. Muneera;K. Sathiyamoorthy;C. Vijayan;Chandrachur Mukherjee
我们报道了在632 nm的低强度连续波激光激发下，用标准的Z扫描技术研究了由有机发色团氨基黑10B组成的客体-宿主系统的固体膜从饱和吸收行为到反饱和吸收行为的转变，该体系由嵌入在乙烯基聚合物聚乙烯醇中的有机发色团构成，并包含聚集的纳米团簇的均匀分布。这归因于样品中存在较高的染料分子聚集态。此外，样品还表现出复杂的非线性折射行为，产生净负非线性，这是基于不同来源的折射非线性可能同时发生的，以及明显的吸收效应。与文献报道的连续波激光激发相比，非线性吸收、非线性折射和三阶非线性极化率的有效系数|χ(3)|的估计值是其中最高的。这些非线性效应可能是这种新的反饱和吸收材料可能应用的基础，这种材料甚至对低功率激发都很敏感，可以作为一种有效的材料用于非线性光学器件。
We report an observed transition from a saturable absorption type of behaviour to a reverse saturable absorption one for solid films of a guest–host system constituted by an organic chromophore, Amido Black 10B, embedded in a vinyl polymer, polyvinyl alcohol, and comprising a uniform distribution of aggregated nanoclusters, as studied using the standard Z-scan technique under low intensity continuous wave laser light excitation at 632 nm, while increasing the concentration of the dye content. This is attributed to the presence of higher aggregates of the dye molecules in the sample. Besides this, the samples also displayed complex nonlinear refraction behaviour, yielding a net negative nonlinearity, explained on the basis of a possible, simultaneous occurrence of refractive nonlinearities of different origin, in addition to the obvious effect of absorption. The estimated values of the effective coefficients of nonlinear absorption, nonlinear refraction and third-order nonlinear susceptibility, |χ(3)|, compared to those reported for continuous wave laser light excitation, measure up to the highest among them. These nonlinear effects could be the basis for possible applications of this new reverse saturable absorption material, sensitive even to low power excitation, as an efficient material for use in nonlinear optical devices.