Engineering polariton non-linearity in organic and hybrid-semiconductor microcavities

强耦合微腔是探索光与物质相互作用的基础物理的一个迷人的系统。在这种情况下，这种微腔中的发射态被称为“极化激元”，并且可以被描述为激子和受限腔光子之间的混合物。极化激元的光学性质可能与其组成部分（激子和腔光子）非常不同，因此有一个重要的机会来探索新的基本过程，并开发新型器件，这些器件可能会在低阈值激光器，光放大器和高速光开关中找到应用。目前，在微腔中强耦合机制方面所做的大部分工作都集中在包含无机半导体（III-V，II-VI或GaN基材料）的结构上。然而，我们率先研究了含有有机（碳基）半导体的强耦合微腔，预计这些微腔可以产生新的效应。尽管有机半导体在一系列光电子器件（LED，光电二极管，FET，激光器等）中的重要性，但对于强耦合有机微腔中发生的微观过程的了解相对较少。因此，对强耦合微腔中有机半导体的非线性过程和性质的基本了解将是我们在本项目中要解决的关键领域。该研究的关键组成部分包括研究有机极化激元与分子半导体振动模式之间的相互作用，以及载流子注入后高密度有机激子极化激元的产生。我们还将探索“混合半导体”微腔和器件（包含有机和无机半导体）的制造和光学特性，并将使用线性和超快测量研究不同类型激发之间的光学驱动能量转移。我们相信，我们的工作将提供新的基本见解有机极化激元的光学性质（包括弛豫和凝聚），不同半导体材料之间的激发通过腔光子在大距离（> 100 nm）和新的电驱动极化激元器件的产生。我们相信，我们是在一个很好的位置进行这样一个雄心勃勃的研究计划，由于我们的世界领先的专业知识，在强耦合有机半导体微腔（谢菲尔德），和双色超快光谱的微腔（南安普顿）。

Strongly-coupled microcavities are a fascinating system for the exploration of the fundamental physics of the interactions between light and matter. Under such circumstances, the emissive states in such microcavities are termed 'polaritons', and can be described as an admixture between an exciton and a confined cavity photon. The optical properties of polaritons can be very different from their constituent parts (excitons and cavity photons), and thus there is a significant opportunity to explore new fundamental processes, and develop new types of devices that may find applications as low-threshold lasers, optical-amplifiers and high-speed optical switches. At present, the majority of work done on the strong-coupling regime in microcavities has centred on structures that contain inorganic semiconductors (either III-V, II-VI or GaN based materials). We have however pioneered the study of strong-coupled microcavities containing organic (carbon-based) semiconductors, which are anticipated permit new effects to be engineered. Despite the importance of organic-semiconductors in a range of optoelectronic devices (LEDs, photovoltaics, FETs, lasers etc) relatively little is understood regarding the microscopic processes that occur in strongly-coupled organic microcavities.Development of a basic understanding of non-linear processes and properties of organic-semiconductors in strongly-coupled microcavities will thus be a key area that we will address in this project. Key components of the research include studies the interactions between organic-polaritons and vibrational modes of the molecular semiconductor and the generation of organic exciton-polaritons at high density following electrical injection of carriers. We will also explore the fabrication and optical properties of 'hybrid-semiconductor' microcavities and devices (containing organic and inorganic semiconductors), and will study optically-driven energy-transfer between the different types of excitation using both linear and ultra-fast measurements. We are confident that our work will provide new fundamental insights into the optical properties of organic-polaritons (including relaxation and condensation), the transfer of excitations between different semiconductor materials via a cavity photon over large distances (> 100 nm) and the generation of new electrically-driven polariton devices. We believe that we are in an excellent position to undertake such an ambitious programme of research due to our world-leading expertise in strongly coupled organic semiconductor microcavities (Sheffield), and two-colour ultra-fast spectroscopy of microcavities (Southampton).