On-chip coherent light source has always been fascinating and intriguing due to its various potential applications. In the past decades, there has been some progress in the development of chip coherent light (e.g., nanolaser, Bose-Einstein condensation and nonlinear optical effects). However, these methods strictly depend on materials and extreme experimental conditions, and are usually not tunable. Here, a hybrid structure is designed which combines a chirped surface plasmon metasurface with a monolayer transition metal dichalcogenide (TMDC) to achieve a coherent second harmonic generation (SHG) covering the entire visible light spectrum. Using only finite number of metallic grooves, a continuous resonance tuning is obtained. By translating the metasurface in space, a space-frequency locking SHG is demonstrated. Although the Q factor of the surface plasmon cavity is low, its near-field enhancements of both fundamental and SH waves are still obvious. Significantly, the broad linewidth of plasmonic cavity leads to a large degree of overlap between adjacent localized modes, that enables the tuning of the output wavelength continuously at room temperature. Meanwhile, the exciton resonance also plays an important role. This monolithic tunable device demonstrates the potentials of 2D material-plasmon hybrid metasurface and to construct an efficient broadband tunable on-chip coherent light source.

中文翻译：

---

覆盖整个可见光范围的 2D 材料 - 等离子混合超表面的二次谐波产生

由于其各种潜在的应用，片上相干光源一直令人着迷。在过去的几十年里，芯片相干光（如纳米激光器、玻色-爱因斯坦凝聚和非线性光学效应）的发展取得了一些进展。然而，这些方法严格依赖于材料和极端的实验条件，通常是不可调谐的。在这里，设计了一种混合结构，将啁啾表面等离子体超表面与单层过渡金属二硫属化物（TMDC）相结合，以实现覆盖整个可见光谱的相干二次谐波（SHG）。仅使用有限数量的金属凹槽，就可以获得连续的共振调谐。通过在空间中平移超表面，展示了空间频率锁定 SHG。尽管表面等离子体腔的 Q 因子较低，但其基波和 SH 波的近场增强仍然很明显。值得注意的是，等离子体腔的宽线宽导致相邻局域模式之间有很大程度的重叠，这使得在室温下连续调谐输出波长成为可能。同时，激子共振也起着重要作用。这种单片可调器件展示了 2D 材料-等离子体混合超表面的潜力，并构建了高效的宽带可调片上相干光源。这使得在室温下连续调谐输出波长成为可能。同时，激子共振也起着重要作用。这种单片可调器件展示了 2D 材料-等离子体混合超表面的潜力，并构建了高效的宽带可调片上相干光源。这使得在室温下连续调谐输出波长成为可能。同时，激子共振也起着重要作用。这种单片可调器件展示了 2D 材料-等离子体混合超表面的潜力，并构建了高效的宽带可调片上相干光源。