纳米PIC-I分子聚集体的超辐射和Z-扫描研究

Study on Superradiation and Z-scan of Nanostructure PIC-I Aggregates

分子聚集体在非线性光学和集成光学等领域有潜在的应用前景。纳米结构一维染料分子J 聚集体有许多既不同于单个分子又不同于体材料的奇异性质,即超辐射和巨光学非线性。这种超辐射是由于在几个本征态内振子强度结合在一起,得到一巨跃迁偶极子,因而是超辐射的。跃迁速率与耦合分子个数N成正比。分子聚集体的J 吸收和超辐射发射是共振的。利用Z 扫描技术测量PIC在不同配比下的非线性折射率、非线性吸收系数和非线性极化率。观测到随着链长变短,样品的三阶非线性极化率增大。对这种非线性增强的机制进行了分析和讨论。

Molecular aggregates have the potential applications on nonlinear opti cs and integrated optics. Unique properties of one dimension nanostructure d ye m olecular Jaggregates are different from either monomers or bulk materials. The unique optical properties of molecular aggregates, not observed in crystals are superradiant emission and giant optical nonlinearities. Superradiance is cause d by the fact that the oscillator strengths of the coupled molecules are swe pt t ogether in a few eigenstates, which thus obtain a giant transition dipole to the ground state and are therefore superadiant: their radiative decay rate enhanc ed linearly with the number of coupled molecules N. Absorption of aggr egates and superradiance are resonant in the spectra. The nonlinear refractive index, absorption coefficiency and polarizibility were measured with Zscan.It is ob served that three order nonlinear polarizibility was increased with chain l engths shortening and the mechani sm was analyzed and discussed.