Biswas Rabindra, Prosad Asish, Krishna Lal A S, Menon Sruti, Raghunathan Varun
Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore 560012, India.
Nanophotonics. 2022 Dec 15;12(1):29-42. doi: 10.1515/nanoph-2022-0459. eCollection 2023 Jan.
The integration of two-dimensional (2D) materials with resonant photonic structures is seen as a promising direction for enhancing its nonlinear optical response. The design of such heterogeneous resonant structures has often relied on multi-parameter sweeps to determine the optimized dimensions of resonant optical structure that results in good resonance characteristics, often in the absence of the 2D material. Such an approach is computationally intensive and may not necessarily result in efficient generation or collection of nonlinear signals from the designed structure. Here, we report hybrid-genetic optimization (HGA) based design and experimental demonstration of second harmonic generation (SHG) enhancement from Fabry-Perot structures of single and double multilayer gallium selenide (GaSe) flakes with bottom silicon dioxide, and index matched polymethyl methacrylate spacer/encapsulation layers. HGA technique utilized here speeds up the multilayer cavity design by 8.8 and 89-times for the single and double GaSe structures when compared to the full parameter-sweep, with measured SHG enhancement of 128- and 400-times, respectively, when compared to a reference sample composed of GaSe layer of optimized thickness on 300 nm silicon dioxide layer. SHG conversion efficiencies obtained from the HGA structures are 1-2 orders of magnitude higher than previous reports on 2D material integrated resonant metasurfaces or Bragg cavities.
将二维（2D）材料与共振光子结构相结合被视为增强其非线性光学响应的一个有前景的方向。这种异质共振结构的设计通常依赖于多参数扫描，以确定能产生良好共振特性的共振光学结构的优化尺寸，而这通常是在没有二维材料的情况下进行的。这种方法计算量很大，而且不一定能从设计的结构中有效地产生或收集非线性信号。在此，我们报告了基于混合遗传优化（HGA）的设计以及对单层和双层多层硒化镓（GaSe）薄片与底部二氧化硅以及折射率匹配的聚甲基丙烯酸甲酯间隔层/封装层组成的法布里 - 珀罗结构中二次谐波产生（SHG）增强的实验演示。与全参数扫描相比，这里使用的HGA技术将单层和双层GaSe结构的多层腔设计速度分别提高了8.8倍和89倍，与由在300 nm二氧化硅层上具有优化厚度的GaSe层组成的参考样品相比，测量到的SHG增强分别为128倍和400倍。从HGA结构获得的SHG转换效率比之前关于二维材料集成共振超表面或布拉格腔的报道高1 - 2个数量级。
