Optical and Quantum Coherence Study of 2D-Material Based Cavity-Enhanced Emitters and Nanolasers

提出的研究旨在了解与a)新兴的单层半导体过渡金属二硫族化合物，b)纳米发射器和纳米激光器发射光的量子光学性质以及c)基于这种单层半导体的纳米激光器的重要器件物理问题相关的一系列基本物理问题。我们将讨论新的活性材料平台的适用性和有前途的材料选择，激光作用在量子光发射特性方面的演示，以及提高离耦效率的器件实现。具有纳米空腔的单层半导体集成系统为提出的研究提供了理想的最先进的平台。该团队由三个优秀的，高度互补的小组组成，分别专门从事二维半导体与量子化光场相互作用的微观理论（Jahnke小组，不来梅大学），纳米激光器的制造和表征（Ning小组，清华大学），以及光发射的量子光学相干研究（Reitzenstein小组Technische Universität Berlin）。从材料制备、器件制造、实验表征到第一性原理理论预测和解释的迭代循环，这个紧密结合的中德团队非常适合以最全面和综合的方式研究上述重要问题。从基础科学的角度来看，预期的结果可能会影响我们对二维单层半导体的光发射和增益机制的基本理解，以及纳米发射器的量子相干性的本质，特别是纳米激光器的阈值行为与量子相干性之间的关系。在这种情况下，我们将讨论如何验证纳米腔激光器中自发发射耦合因子（β因子）接近于无阈值激光器极限情况的统一的激光作用的重要问题。半导体激光器的这一基本机制将通过对发射光子统计的全面量子光学研究来探索，作为最敏感的工具来明确识别相干光发射的开始。除了输入输出和线宽依赖关系外，通过考虑发射的光子数分布，联合实验和理论工作将使对纳米激光器发射过程的理解达到一个新的水平。在这里，光子数分布提供了完整的光子统计，包括高阶光子相关。这项工作将由Reitzenstein小组高度先进的光子数分辨探测器实现。从技术的角度来看，所提出的研究可能导致应用于下一代信息技术的新型纳米光子器件，或量子信息技术中的新型器件。

The proposed research aims at the understanding of a series of fundamental physics questions related to a) the emerging monolayer semiconductor transition metal dichalcogenides, b) quantum optical properties of light emission from nanoemitters and nanolasers, as well as c) important device physics issues of nanolasers based on such monolayer semiconductors. We will address the suitability of the new active-material platform and promising material choices, the demonstration of laser action in terms of quantum-optical emission properties, and device realizations with improved outcoupling efficiencies. The integrated system of monolayer semiconductors with nanocavities provides an ideal state-of-the-art platform for the proposed study. The team consists of three well qualified, highly complementary groups specializing in microscopic theory of 2D semiconductors interacting with quantized light field (Jahnke group, University of Bremen), fabrication, and characterization of nanolasers (Ning group, Tsinghua University), and quantum optical coherence study of light emission (Reitzenstein group Technische Universität Berlin), respectively. The well-knit Sino-German team is uniquely suited to investigate the important questions raised above in the most comprehensive and integrative manner through an iterative cycle from materials preparation, device fabrication, experimental characterization, and first-principle theoretical prediction and interpretation. From the fundamental science point of view, the expected results can potentially impact our basic understanding of light emission and gain mechanism in 2D monolayer semiconductors, as well as the nature of quantum coherence of nanoemitters, especially the relationship between threshold behavior of the nanolasers and quantum coherence. In this context, we will address the important issue of how to verify laser action in nanocavity lasers with spontaneous emission coupling factors (beta-factor) approaching unity close to the limiting case of a thresholdless laser. This fundamental regime of semiconductor lasers will be explored by comprehensive quantum optical studies on the photon statistics of emission, acting as the most sensitive tool to unambiguously identify the onset of coherent light emission. The joint experimental and theoretical work will aim at a new level of understanding the emission processes of nanolaser by considering the photon-number distribution of emission in addition to input-output and linewidth dependencies. Here, the photon-number distribution gives access to the full photon statistic including higher order photon correlations. This work will be enabled by highly advanced photon-number resolving detectors in the Reitzenstein group. From the technological point of view, the proposed research could lead to a new type of nanophotonic devices for applications in next generation of information technologies, or novel devices in quantum information technologies.