Dual bound states in the continuum enhanced second harmonic generation with Transition Metal Dichalcogenides monolayer
Dual bound states in the continuum enhanced second harmonic generation with Transition Metal Dichalcogenides monolayer
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DOI：
10.29026/oea.2022.200097
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发表时间：
2020
影响因子：
14.1
通讯作者：
P. Hong;Lei Xu;M. Rahmani
中科院分区：
文献类型：
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作者：
P. Hong;Lei Xu;M. Rahmani
二维（2D）材料的出现为在纳米尺度下展示二次谐波产生（SHG）开辟了新的可能性，这是由于它们在室温下与稳定激子相关的显著光学响应。然而，最终的原子尺度与光的相互作用长度使得过渡金属二硫属化物（TM-Ds）单分子膜的SHG自然较弱。在这里，我们提出了一个单层的TMD与光子光栅板，工作在连续（BIC）的双共振束缚态耦合。BIC板被设计成呈现一对BIC，与基波（FW）和二次谐波（SHW）两者谐振。首先，通过倾斜FW的入射角来实现空间模式匹配。我们从理论上证明，这种策略导致超过四个数量级的提高SHG效率比单一单层的TMD，在泵浦光强度为0.1 GW/cm 2。此外，我们证明，图案化的TMD单层可以进一步提高空间重叠系数，这导致了额外的三个数量级的提高SHG效率。这些结果证明了用非线性2D材料增强SHG的显著可能性，为基于芯片的光源，纳米激光器，成像和生化传感提供了许多机会。
The emergence of two dimensional (2D) materials has opened new possibilities for exhibiting second harmonic generation (SHG) at the nanoscale, due to their remarkable optical response related to stable excitons at room temperature. However, the ultimate atomic-scale interaction length with light makes the SHG of Transition Metal Dichalcogenides (TM-Ds) monolayers naturally weak. Here, we propose coupling a monolayer of TMDs with a photonic grating slab that works with doubly resonant bound states in the continuum (BIC). The BIC slabs are designed to exhibit a pair of BICs, resonant with both the fundamental wave (FW) and the second harmonic wave (SHW). Firstly, the spatial mode matching can be fulfilled by tilting FW's incident angle. We theoretically demonstrate that this strategy leads to more than four orders of magnitude enhancement of SHG efficiency than a sole monolayer of TMDs, under a pump light intensity of 0.1 GW/cm 2 . Moreover, we demonstrate that patterning the TMDs monolayer can further enhance the spatial overlap coefficient, which leads to an extra three orders of magnitude enhancement of SHG efficiency. These results demonstrate remarkable possibilities for enhancing SHG with nonlinear 2D materials, opening many opportunities for chip-based light sources, nano-lasers, imaging, and biochemical sensing.