Optical valley Hall effect for highly valley-coherent exciton-polaritons in an atomically thin semiconductor
Optical valley Hall effect for highly valley-coherent exciton-polaritons in an atomically thin semiconductor
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DOI：
10.1038/s41565-019-0492-0
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发表时间：
2019-08-01
影响因子：
38.3
通讯作者：
Schneider, Christian
中科院分区：
文献类型：
--
作者：
Lundt, Nils;Dusanowski, Lukasz;Schneider, Christian
自旋-轨道耦合是连接电荷载流子的自旋与其动量的基本机制。在光学领域，通过在光子材料中设计光学各向异性，可以获得类似的合成自旋轨道耦合。两者都产生了创造直接利用自旋和极化作为信息载体的设备的可能性。原子薄的过渡金属二硫属化物承诺固有的自旋谷霍尔功能的自由载流子，激子和光子。在这里，我们证明了自旋和谷选择性传播激子极化激元在单层的MoSe 2是强耦合到微腔光子模式。在一个线状器件中，我们追踪了激子-极化激元沿其通道沿着扩展的流动和螺旋度。通过激发相干叠加的K和K'标记的极化激元，我们观察到谷选择性膨胀的极化激元云没有外部磁场或相干瑞利散射。所观察到的光谷霍尔效应发生在宏观尺度上，提供了潜在的自旋谷锁定光子器件的应用。
Spin-orbit coupling is a fundamental mechanism that connects the spin of a charge carrier with its momentum. In the optical domain, an analogous synthetic spin-orbit coupling is accessible by engineering optical anisotropies in photonic materials. Both yield the possibility of creating devices that directly harness spin and polarization as information carriers. Atomically thin transition metal dichalcogenides promise intrinsic spin-valley Hall features for free carriers, excitons and photons. Here we demonstrate spin- and valley-selective propagation of exciton-polaritons in a monolayer of MoSe2 that is strongly coupled to a microcavity photon mode. In a wire-like device we trace the flow and helicity of exciton-polaritons expanding along its channel. By exciting a coherent superposition of K and K' tagged polaritons, we observe valley-selective expansion of the polariton cloud without either an external magnetic field or coherent Rayleigh scattering. The observed optical valley Hall effect occurs on a macroscopic scale, offering the potential for applications in spin-valley-locked photonic devices.