Simbulan Kristan Bryan, Huang Teng-De, Peng Guan-Hao, Li Feng, Gomez Sanchez Oscar Javier, Lin Jhen-Dong, Lu Chun-I, Yang Chan-Shan, Qi Junjie, Cheng Shun-Jen, Lu Ting-Hua, Lan Yann-Wen
Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan.
Department of Mathematics and Physics, University of Santo Tomas, Manila 1008, Philippines.
ACS Nano. 2021 Feb 23;15(2):3481-3489. doi: 10.1021/acsnano.0c10823. Epub 2021 Feb 10.
Twisted light carries a well-defined orbital angular momentum (OAM) of per photon. The quantum number of its OAM can be arbitrarily set, making it an excellent light source to realize high-dimensional quantum entanglement and ultrawide bandwidth optical communication structures. In spite of its interesting properties, twisted light interaction with solid state materials, particularly two-dimensional materials, is yet to be extensively studied experiments. In this work, photoluminescence (PL) spectroscopy studies of monolayer molybdenum disulfide (MoS), a material with ultrastrong light-matter interaction due to reduced dimensionality, are carried out under photoexcitation of twisted light. It is observed that the measured spectral peak energy increases for every increment of of the incident light. The nonlinear -dependence of the spectral blue shifts is well accounted for by the analysis and computational simulation of this work. More excitingly, the twisted light excitation revealed the unusual lightlike exciton band dispersion of valley excitons in monolayer transition metal dichalcogenides. This linear exciton band dispersion is predicted by previous theoretical studies and evidenced this work's experimental setup.
扭曲光每个光子携带明确的轨道角动量（OAM）。其OAM的量子数可以任意设定，使其成为实现高维量子纠缠和超宽带宽光通信结构的理想光源。尽管具有有趣的特性，但扭曲光与固态材料，特别是二维材料的相互作用尚未通过实验进行广泛研究。在这项工作中，在扭曲光的光激发下，对单层二硫化钼（MoS）进行了光致发光（PL）光谱研究，MoS是一种由于维度降低而具有超强光与物质相互作用的材料。观察到，随着入射光每增加 ，测量到的光谱峰值能量都会增加。通过这项工作的分析和计算模拟，很好地解释了光谱蓝移的非线性 依赖性。更令人兴奋的是，扭曲光激发揭示了单层过渡金属二卤化物中谷激子不寻常的类光激子能带色散。这种线性激子能带色散是先前理论研究所预测的，并在这项工作的实验装置中得到了证实。
