Experimental Verification of the Very Strong Coupling Regime in a GaAs Quantum Well Microcavity.
Experimental Verification of the Very Strong Coupling Regime in a GaAs Quantum Well Microcavity.
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GaAs 量子阱微腔中强耦合机制的实验验证。
DOI：
10.1103/physrevlett.119.027401
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发表时间：
2017
影响因子：
8.6
通讯作者：
Brodbeck S
中科院分区：
文献类型：
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作者：
Brodbeck S
腔光子和量子阱激子之间的偶极子耦合强度决定了量子阱微腔中光物质耦合的状态。在强耦合状态下，激子和腔光子之间发生可逆能量转移，从而导致混合极化子共振的形成。如果进一步增加耦合，就会出现不同单激子态的杂化，这被称为极强耦合机制。在半导体量子阱中，当耦合强度与激子结合能的比率接近1时，这种状态预计表现为光子介导的电子-空穴耦合，导致两个极化子分支的激子波函数不同。在这里，我们通过实验验证了微腔磁光测量中这种状态的存在，其特征在于，表明与裸量子阱激子玻尔半径相比，上极化子的平均电子空穴分离显着增加。这会产生大约 0 失谐的抗磁位移，该位移超过下极化子的位移 1 个数量级，并且超过裸量子阱激子抗磁位移的 2 倍。下极化子表现出的抗磁位移小于刚性激子与腔模式耦合的预期，这表明电子-空穴对比裸量子阱中束缚更紧密。
The dipole coupling strengthbetween cavity photons and quantum well excitons determines the regime of light matter coupling in quantum well microcavities. In the strong coupling regime, a reversible energy transfer between exciton and cavity photon takes place, which leads to the formation of hybrid polaritonic resonances. If the coupling is further increased, a hybridization of different single exciton states emerges, which is referred to as the very strong coupling regime. In semiconductor quantum wells such a regime is predicted to manifest as a photon-mediated electron-hole coupling leading to different excitonic wave functions for the two polaritonic branches when the ratio of the coupling strength to exciton binding energyapproaches unity. Here, we verify experimentally the existence of this regime in magneto-optical measurements on a microcavity characterized by, showing that the average electron-hole separation of the upper polariton is significantly increased compared to the bare quantum well exciton Bohr radius. This yields a diamagnetic shift around 0 detuning that exceeds the shift of the lower polariton by 1 order of magnitude and the bare quantum well exciton diamagnetic shift by a factor of 2. The lower polariton exhibits a diamagnetic shift smaller than expected from the coupling of a rigid exciton to the cavity mode, which suggests more tightly bound electron-hole pairs than in the bare quantum well.