Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil.
Instituto de Química e Biotecnologia, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil.
Phys Rev E. 2017 Dec;96(6-1):062703. doi: 10.1103/PhysRevE.96.062703. Epub 2017 Dec 18.
The present study is devoted to the investigation of the nonlinear optical properties of a smectic liquid crystal doped with gold nanorods. Using the Z-scan technique, we investigate the changes in the optical birefringence of a homeotropic sample upon laser exposure, considering the configurations of normal and oblique incidence. Our results reveal that the birefringence variations may be governed by distinct physical mechanisms, depending on the relative angle between the far-field director and the wave vector of the excitation laser beam. In particular, we observe that the position dependence of the far-field transmittance exhibits different behaviors as the incidence angle is changed, indicating that distortions in the beam wavefront may be associated with the thermal lens phenomenon or an optically induced reorientation of the nematic director. The temperature dependence of the nonlinear refractive and absorptive coefficients is investigated close to the smectic-A-nematic phase transition. A detailed analysis of the interplay between smectic order and plasmon resonance is performed, thus unveiling the capability of plasmonic liquid crystal to be used in optical devices.
本研究致力于研究掺杂金纳米棒的向列相液晶的非线性光学性质。我们使用 Z 扫描技术，研究了激光辐照下各向异性样品的光学双折射变化，同时考虑了正常和斜入射的情况。我们的结果表明，双折射变化可能由不同的物理机制控制，这取决于远场指向矢与激发激光束波矢之间的相对角度。特别是，我们观察到远场透射率的位置依赖性随着入射角的变化呈现出不同的行为，这表明光束波前的变形可能与热透镜现象或向列相指向矢的光诱导重取向有关。我们还研究了接近近晶 A-向列相转变时的非线性折射和吸收系数的温度依赖性。我们对近晶有序和等离子体共振之间的相互作用进行了详细分析，从而揭示了等离子体液晶在光电器件中的应用潜力。
