Almeida Euclides, Prior Yehiam
Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
Sci Rep. 2015 May 14;5:10033. doi: 10.1038/srep10033.
Optimizing the shape of nanostructures and nano-antennas for specific optical properties has evolved to be a very fruitful activity. With modern fabrication tools a large variety of possibilities is available for shaping both nanoparticles and nanocavities; in particular nanocavities in thin metal films have emerged as attractive candidates for new metamaterials and strong linear and nonlinear optical systems. Here we rationally design metallic nanocavities to boost their Four-Wave Mixing response by resonating the optical plasmonic resonances with the incoming and generated beams. The linear and nonlinear optical responses as well as the propagation of the electric fields inside the cavities are derived from the solution of Maxwell's equations by using the 3D finite-differences time domain method. The observed conversion-efficiency of near-infrared to visible light equals or surpasses that of BBO of equivalent thickness. Implications to further optimization for efficient and broadband ultrathin nonlinear optical materials are discussed.
优化纳米结构和纳米天线的形状以获得特定光学特性已成为一项卓有成效的工作。借助现代制造工具，塑造纳米颗粒和纳米腔有多种可能性；特别是，金属薄膜中的纳米腔已成为新型超材料以及强线性和非线性光学系统的有吸引力的候选者。在此，我们合理设计金属纳米腔，通过使光学等离子体共振与入射光束和产生的光束共振来增强其四波混频响应。通过使用三维时域有限差分法求解麦克斯韦方程组，得出了腔内的线性和非线性光学响应以及电场传播。观察到的近红外到可见光的转换效率等于或超过了同等厚度的BBO晶体。讨论了对高效宽带超薄非线性光学材料进一步优化的意义。
