论文标题
波导耦合单层WSE2中的内部和谷中激子之间的上下转换
Up- and Down-Conversion between Intra- and Inter-Valley Excitons in Waveguide Coupled Monolayer WSe2
论文作者
论文摘要
单层（1L）过渡金属二北元元素（TMD）半导体中存在两个自旋分裂山谷，支持通过其自旋和山谷量子数分类的多功能激子物种。虽然很容易观察到Spin-0 Interavalley激子（称为“明亮”激子），但其他类型的激子，例如Spin-1 Interavalley（Spin-Dark）和Spin-0 Intervalley（Momentum-Dark）激子激子，更难以访问。在这里，我们开发了一个波导耦合的1L钨氧化氢（WSE2）设备，以探测这些激子物种。特别是，与原子层的平面外偶极矩相连，使我们不仅能够有效收集，而且可以共同收集Spin-1 Dark Ickiton，这有望在开发具有长山谷寿命的设备。我们的工作揭示了几个上转换过程，这些过程带来了一个复杂的耦合网络，该耦合网络将Spin-0和Spin-1内部和valley激子连接起来，这表明Intervalley散射和Spin-Flip是原子层中非常常见的过程。这些实验结果加深了我们对Dungsten duselenide激子物理学的理解，并说明平面光子设备能够利用TMD半导体中的多功能激子物种。
The presence of two spin-split valleys in monolayer (1L) transition metal dichalcogenide (TMD) semiconductors supports versatile exciton species classified by their spin and valley quantum numbers. While the spin-0 intravalley exciton, known as the "bright" exciton, is readily observable, other types of excitons, such as the spin-1 intravalley (spin-dark) and spin-0 intervalley (momentum-dark) excitons, are more difficult to access. Here we develop a waveguide coupled 1L tungsten diselenide (WSe2) device to probe these exciton species. In particular, TM coupling to the atomic layer's out-of-plane dipole moments enabled us to not only efficiently collect, but also resonantly populate the spin-1 dark excitons, promising for developing devices with long valley lifetimes. Our work reveals several upconversion processes that bring out an intricate coupling network linking spin-0 and spin-1 intra- and inter-valley excitons, demonstrating that intervalley scattering and spin-flip are very common processes in the atomic layer. These experimental results deepen our understanding of tungsten diselenide exciton physics and illustrate that planar photonic devices are capable of harnessing versatile exciton species in TMD semiconductors.
