Spin-dependent polariton scattering and all-optical control of transverse patterns in semiconductor microcavities

本项目主要研究相干驱动微腔极化子系统中模式的形成和光学控制。基于量子阱的半导体微腔在量子阱平面上是空间均匀的。正入射平面波泵浦激励不破坏平面内的平动和旋转对称性。然而，对于下极化子分支以上的泵浦激发光谱，系统可以自发地打破其对称性，表现出空间非均匀的非线性光学响应：在一定的泵浦阈值强度以上，泵浦诱导的极化子的受激离轴散射克服了离轴模式的本征损失，使离轴信号自发地建立起来，并以有限的角度从腔中发射出去。详细研究驱动非线性系统产生的自组织和相关的模式形成是本课题的目的。在该项目的第一个资助期已经获得了重要的见解。在项目继续中，我们将特别关注模式形成中与自旋相关的方面。目的是实现对潜在微观物理的深刻理解，并探索如何使用旋量效应来控制模式，例如，用于全光开关。我们的理论工作将与实验合作者密切合作。

This project is focussed on the formation and optical control of patterns in coherently driven microcavity polariton systems. Quantum-well based semiconductor microcavites are spatially homogeneous in the quantum-well plane. Plane-wave pump excitation in normal incidence does not spoil the translational and rotational symmetry in the plane. Nevertheless, for pump excitation spectrally above the lower polariton branch, the system can spontaneously break its symmetry and show a spatially non-homogeneous nonlinear optical response: above a certain pump threshold intensity, stimulated off-axis scattering of pump-induced polaritons overcomes the intrinsic losses in the off-axis modes such that off-axis signals spontaneously build up and are emitted from the cavity under a finite angle. It is the purpose of this project to study in detail the resulting self-organization in the driven nonlinear system and related pattern formation. Important insights were already obtained in the first funding period of this project. In the project continuation we will particularly focus on spin-dependent aspects of the pattern formation. Aim is to achieve a deep understanding of the underlying microscopic physics and explore how spinor effects can be used to control the patterns, e.g., for all-optical switching. Our theoretical work will be done closely together with our experimental collaborators.