Liu Zhuojun, Chen Bo, Wang Xuying, Qiu Guixin, Cao Qitao, Wei Dunzhao, Liu Jin
State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing 100871, China.
State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, School of Electronics and Information Technology, Sun Yat-Sen University, Guangzhou 510275, China.
Nanophotonics. 2024 Aug 5;13(21):4029-4035. doi: 10.1515/nanoph-2024-0282. eCollection 2024 Sep.
Two-dimensional (2D) layered materials without centrosymmetry, such as GaSe, have emerged as promising novel optical materials due to large second-order nonlinear susceptibilities. However, their nonlinear responses are severely limited by the short interaction between the 2D materials and light, which should be improved by coupling them with photonic structures with strong field confinement. Here, we theoretically design photonic crystal circular Bragg gratings (CBG) based on hole gratings with a quality factor as high as = 8 × 10, a mode volume as small as = 1.18 (/), and vertical emission of light field in silicon nitride thin film platform. Experimentally, we achieved a value up to nearly 4 × 10, resulting in a 1,200-fold enhancement of second harmonic generation from GaSe flakes with a thickness of 50 nm coupling to the CBG structures under continuous-wave excitation. Our work endows silicon-based photonic platforms with significant second-order nonlinear effect, which is potentially applied in on-chip quantum light sources and nonlinear frequency conversion.
诸如GaSe之类的无中心对称二维（2D）层状材料，由于具有较大的二阶非线性极化率，已成为有前景的新型光学材料。然而，它们的非线性响应受到二维材料与光之间短相互作用的严重限制，应通过将它们与具有强场限制的光子结构耦合来加以改善。在此，我们从理论上设计了基于空穴光栅的光子晶体圆形布拉格光栅（CBG），其品质因数高达 = 8×10，模式体积小至 = 1.18 （/），并且在氮化硅薄膜平台中实现光场的垂直发射。在实验中，我们实现了高达近4×10的值，使得在连续波激发下，与CBG结构耦合的厚度为50 nm的GaSe薄片的二次谐波产生增强了1200倍。我们的工作赋予硅基光子平台显著的二阶非线性效应，这在片上量子光源和非线性频率转换中具有潜在应用。
