Second Harmonic and Sum-Frequency Generations from a Silicon Metasurface Integrated with a Two-Dimensional Material
Second Harmonic and Sum-Frequency Generations from a Silicon Metasurface Integrated with a Two-Dimensional Material
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二维材料集成硅亚表面产生的二次谐波和频率
DOI：
10.1021/acsphotonics.9b00553
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发表时间：
2019-04
期刊：
影响因子：
7
通讯作者：
Qingchen Yuan;Liang Fang;Hanlin Fang;Juntao Li;Tao Wang;W. Jie;Jianlin Zhao;Xuetao Gan
中科院分区：
文献类型：
--
作者：
Qingchen Yuan;Liang Fang;Hanlin Fang;Juntao Li;Tao Wang;W. Jie;Jianlin Zhao;Xuetao Gan
由于晶体中心对称性，硅基非线性超表面仅具有三阶非线性，效率相当低，这阻碍了其在低功率激光器的实际应用。在这里，我们建议将二维 GaSe 薄片集成到硅超表面上，以辅助高效的二阶非线性过程，包括二次谐波生成（SHG）和和频生成（SFG）。通过谐振泵浦支持法诺共振的集成 GaSe 超表面，所获得的倍频比裸硅超表面产生的三次谐波强约两个数量级。此外，由于谐振场增强和GaSe强大的二阶非线性，集成结构的SHG可以用低功率连续波激光器成功激发，这使得进一步实现SFG成为可能。二维材料辅助的高效二阶非线性过程具有扩展硅超表面在非线性领域功能的潜力。
Silicon-based nonlinear metasurfaces were implemented only with third-order nonlinearity due to the crystal centrosymmetry and the efficiencies are considerably low, which hinders their practical applications with low-power lasers. Here, we propose to integrate a two-dimensional GaSe flake onto a silicon metasurface to assist high-efficiency second-order nonlinear processes, including second-harmonic generation (SHG) and sum-frequency generation (SFG). By resonantly pumping the integrated GaSe-metasurface, which supports a Fano resonance, the obtained SHG is about two orders of magnitude stronger than the third-harmonic generation from the bare silicon metasurface. In addition, thanks to the resonant field enhancement and GaSe's strong second-order nonlinearity, SHG of the integrated structure could be excited successfully with a low-power continuous-wave laser, which makes it possible to further implement SFG. The high-efficiency second-order nonlinear processes assisted by two-dimensional materials present potentials to expand silicon metasurface's functionalities in nonlinear regime.