Opt Lett. 2023 Jun 1;48(11):3095-3098. doi: 10.1364/OL.489777.
Colloidal semiconductor quantum dots (QDs), with a size tunable bandgap and remarkably high quantum efficiency, have been recognized as ideal light sources in quantum information and light emitting devices. For light sources, besides the emission intensity and spectral profile, the degree of polarization (DoP) is an essential parameter. Here, by embedding a monolayer of QDs inside the nanogap between a bottom Au mirror and a top Ag nanowire, we have demonstrated highly polarized light emission from the QDs with an average DoP of 0.89. In addition to the anisotropic photoluminescence (PL) intensity, the PL spectra are distinct at different polarizations, with an asymmetric spectral shape or even two-peak features. Such an anisotropic emission behavior arises from the coupling between the QDs and the largely confined and polarization-dependent gap-plasmons in the Au/QD/Ag nanocavities in the intermediate coupling regime. Our results demonstrate the possibility of achieving highly polarized light sources by coupling spherical QDs to single anisotropic plasmonic nanocavities, to provide new opportunities in the future design of polarized QD-based display devices.
胶体半导体量子点（QDs）具有可调带隙和极高量子效率的特点，已被公认为量子信息和发光器件中的理想光源。对于光源来说，除了发射强度和光谱分布外，偏振度（DoP）也是一个重要的参数。在这里，我们通过在底部金镜和顶部银纳米线之间的纳米间隙内嵌入一层量子点，实现了来自量子点的高度偏振光发射，其平均偏振度为 0.89。除了各向异性的光致发光（PL）强度外，PL 光谱在不同偏振下也有明显的区别，具有不对称的光谱形状，甚至双峰特征。这种各向异性的发射行为源于量子点与 Au/QD/Ag 纳米腔中高度受限且偏振相关的间隙等离子体之间的耦合，这种耦合处于中等耦合状态。我们的结果表明，通过将球形量子点与单个各向异性等离子体纳米腔耦合，可以实现高度偏振的光源，这为基于偏振量子点的显示器件的未来设计提供了新的机会。
