Multimode dynamics of semiconductor quantum-dot lasers

本课题将研究基于半导体量子点的多模激光器的动力学。半导体量子点是纳米尺寸的半导体结构，可以外延生长并根据特定要求定制。它们的小尺寸导致离散电子能态的形成，产生类似原子的光学跃迁。与传统的半导体激光材料相比，量子点具有发射波长的高可调性、宽增益谱和高动态稳定性。基于量子点的光电器件非常适合于纠缠光子对的产生、单光子的产生和安全量子通信。在传统通信中，基于量子点的光放大器可用于比特率超过100Gb/s的光数据通信，因为其光增益恢复速度超快。量子点的局域性使它们容易受到空间非均质性的影响，因为它们在激光腔中由于光场的驻波模式而自然产生。量子点介质与这种非均匀性的相互作用导致多模动力学的形成，即同时发射多个激光波长。这可以导致新的动态效应，无论是在自由运行的激光或当光学扰动存在，如光反馈或外部光注入。该项目的目的是研究在这些条件下半导体量子点激光器的多模动力学，从理论上和实验上。为此，将推导一个有效的数值模型，描述激光动力学和不同激光模式的相互作用，以及复杂的量子点动力学。该模型将应用于并与项目期间进行的测量收集的实验数据进行比较。所得结果对未来基于半导体量子点的光电子设计具有重要意义。

In this project, the dynamics of multi-mode lasers based on semiconductor quantum-dots will be investigated. Semiconductor quantum-dots are nanometre-sized semiconductor structures that can be grown epitaxially and tailored to specific requirements. Their small size leads to the formation of discrete electronic energy states, yielding atom-like optical transitions. In contrast to conventional semiconductor laser materials, quantum dots offer a high tunability of the emission wavelength, a broad gain spectrum, and high dynamical stability. Optoelectronic devices based on quantum dots are well suited for generation of entangled photon pairs, single-photon generation, and secure quantum communication. In traditional telecommunications, quantum-dot based optical amplifiers can be used for optical data communication with bit rates exceeding 100Gb/s, owing to the ultra-fast recovery of the optical gain.The localized nature of quantum dots makes them susceptible to spatial inhomogeneities, as they arise naturally in laser cavities due to the standing wave pattern of the optical field. The interaction of the quantum-dot medium with such inhomogeneities leads to the formation of multi-mode dynamics, i.e. the emission of several lasing wavelengths at once. This can lead to new dynamic effects, either in the free-running laser or when optical perturbations are present, such as optical feedback or external optical injection.The aim of the project is to investigate the multi-mode dynamics of semiconductor quantum-dot lasers under these conditions, both theoretically and experimentally. To this end, an efficient numerical model will be derived, describing the laser dynamics and the interplay of different laser modes, as well as the complex quantum-dot dynamics. This model will be applied to and compared with experimental data gathered from measurements performed during the project. The obtained results will be of great importance for future design of optoelectronics based on semiconductor quantum dots.