Nanoscale optomechanical interactions in semiconductor microcavities

微腔激子极化子是半导体微腔中量子阱激子与光子强耦合产生的玻色子物质波激发。因此，极化子将光子的长空间相干性与激子成分产生的强烈的粒子间相互作用结合在一起。低有效质量和玻色子性质使得在较低的粒子密度和较高的温度(即(Al，Ga)As结构的液态氦温度)下形成具有长空间(数十m)和时间(100‘pS的S)相干的极化子凝聚体。本项目的目的是研究沿结构极化子MC的间隔层引导的极化子(及其凝聚体)和纵向声学声子(表示为间隙)之间的共振声光相互作用。我们将开发一种新的极化-声子耦合平台，使高密度的极化和声子同时限制在同一空间位置。在这个平台中，光谱窄的极化共振(特别是在凝聚区域)将能够以高灵敏度检测间隙效应。该平台将用于访问共振声光相互作用的两个互补方面。第一部分研究了GHz带隙对极化子的调制作用，以形成动态极化子晶格。这些可调谐晶格可以看作是冷原子光学晶格的固态类似物。支持高频(几GHz)和亚微米波长声子的极化声子-声子平台将提供进入小空间和时间调制周期的制度，这在现有的调制方案中是不可能的。该项目的第二个方面将利用高偏振子密度引起的强烈声光背作用来控制结构MC中能隙的产生、传播和引导。

Microcavity exciton polaritons (to be denoted as polaritons) are bosonic matter-wave excitations resulting from the strong coupling between quantum well (QW) excitons and photons in a semiconductor microcavity (MC). Polaritons thus combine the long spatial coherence of photons with strong inter-particle interactions resulting from the excitonic component. The low effective mass together with the bosonic character enables the formation of polariton condensates with long spatial (tens of m) and time (100’s of ps) coherences at relatively low particle densities and high temperatures (i.e., liquid He temperatures for (Al,Ga)As structures). The objective of the present project is to investigate the resonant acousto-optical interaction between polaritons (and their condensates) and longitudinal acoustic phonons (denoted as gAPs) guided along the spacer layer of a structured polariton MC. We will develop a new platform for polariton-phonon coupling, which enables the simultaneous confinement of a high density of polaritons and phonons at the same spatial location. In this platform, the spectrally narrow polariton resonances (in particular, in the condensation regime) will enable the detection of gAP effects with high sensitivity. The platform will be used for accessing two complementary aspects of the resonant acousto-optical interactions. The first explores the modulation of polaritons by GHz gAPs for the formation of dynamic polariton lattices. These tunable lattices can be regarded as solid-state analogs to optical lattices of cold atoms. The polariton-phonon platform supporting high frequency (several GHz) and sub-micrometer wavelengths phonons will provide access to a regime of small spatial and time modulation periods, not possible in existing modulation schemes. The second aspect of the project will take advantage of the strong acousto-optic back-action induced by the high polariton density to control the generation, propagation, and guiding of gAPs in structured MCs.