Mohan Sabitha, Lange Jens, Graener Heinrich, Seifert Gerhard
Physics Institute, Martin-Luther-University Halle-Wittenberg, D-06099 Halle, Germany.
Opt Express. 2012 Dec 17;20(27):28655-63. doi: 10.1364/OE.20.028655.
The nonlinear optical properties of nanocomposites consisting of non-spherical silver nanoparticles in glass matrix have been studied using the femtosecond Z-scan technique. The spheroidal nanoparticles were uniformly oriented along a common direction. By polarization sensitive studies, longitudinal and transverse plasmon resonances can be addressed separately. A sign reversal in optical nonlinearity from negative to positive is observed while switching the light interaction from near to non-resonant regime, which can be done by simply rotating the light polarization by 90°. Studying samples with different aspect ratio, we obtained the dispersion of third-order nonlinearity in the near-resonant regime, showing an enhancement of the nonlinear processes by more than two orders of magnitude due to the electric field enhancement at the surface plasmon resonance.
利用飞秒Z扫描技术研究了玻璃基质中由非球形银纳米颗粒组成的纳米复合材料的非线性光学特性。这些椭球形纳米颗粒沿共同方向均匀取向。通过偏振敏感研究，可以分别研究纵向和横向等离子体共振。当将光相互作用从近共振状态切换到非共振状态时，观察到光学非线性从负到正的符号反转，这可以通过简单地将光偏振旋转90°来实现。通过研究具有不同纵横比的样品，我们获得了近共振状态下三阶非线性的色散，结果表明由于表面等离子体共振处的电场增强，非线性过程增强了两个以上数量级。
