Transition metal dichalcogenides (TMD) heterostructure is widely applied for second harmonic generation (SHG) and holds great promises for laser source, nonlinear switch, and optical logic gate. However, for atomically thin TMD heterostructures, low SHG conversion efficiency would occur due to reduction of light—matter interaction length and lack of phase matching. Herein, we demonstrated a facile directional SHG amplifier formed by MoS₂/WS₂ monolayer heterostructures suspended on a holey SiO₂/Si substrate. The SHG enhancement factor reaches more than two orders of magnitude in a wide spectral range from 355 to 470 nm, and the radiation angle is reduced from 38° to 19° indicating higher coherence and better emission directionality. The giant SHG enhancement and directional emission are attributed to the great excitation and emission field concentration induced by a self-formed vertical Fabry—Pérot microcavity. Our discovery gives helpful insights for the development of two-dimensional (2D) nonlinear optical devices.

过渡金属二硫属化物（TMD）异质结构广泛应用于二次谐波产生（SHG），并在激光源、非线性开关和光逻辑门等方面有很大的应用前景。然而，对于原子级薄的 TMD 异质结构，由于光物质相互作用长度的减少和相位匹配的缺乏，会出现低 SHG 转换效率。_{在此，我们展示了一种由悬浮在多孔SiO 2}上的MoS ₂ /WS ₂单层异质结构形成的简易定向SHG放大器。/Si衬底。SHG增强因子在355-470 nm的宽光谱范围内达到两个数量级以上，辐射角从38°减小到19°，表明更高的相干性和更好的发射方向性。巨大的 SHG 增强和定向发射归因于自形成的垂直 Fabry-Pérot 微腔引起的巨大激发和发射场集中。我们的发现为二维 (2D) 非线性光学器件的开发提供了有益的见解。