Exciton polaritons in a CuBr microcavity with HfO_2/SiO_2 distributed Bragg reflectors
Exciton polaritons in a CuBr microcavity with HfO_2/SiO_2 distributed Bragg reflectors
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具有 HfO_2/SiO_2 分布布拉格反射器的 CuBr 微腔中的激子极化子
DOI：
10.1103/physrevb.85.205320
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
and D. Kim
中科院分区：
文献类型：
--
作者：
M. Nakayama;Y. Kanatani;T. Kawase;and D. Kim
我们研究了由有效厚度为λ/2的CuBr有源层和HfO/SiO分布布拉格反射镜组成的CuBr体微腔中激子-光子强耦合的特性：λ对应于最低激子的有效共振波长。CuBr晶体在Γ点有三个激子，分别被标记为Z、Z和Z，其中Z激子起源于三重态，这是CuBr所特有的。在10K测量的角度分辨反射光谱表明，Z、Z和Z激子与腔光子的强耦合行为导致了四个腔-极化子分支的形成。基于强耦合唯象哈密顿量分析了腔-极化子的色散关系，得到Z、Z和Z激子的真空拉比分裂能分别为31、108和84 meV。这些拉比分裂能反映了相关激子振子强度的大小。此外，我们还精确地测量了弱激发条件下下极化子分支的角分辨光致发光(PL)光谱。在瓶颈区，腔极化子的布居可以忽略不计，在=0处的光致发光强度最高。这些事实表明，腔极化子的驰豫过程不受瓶颈效应的影响。
We have investigated the characteristics of exciton-photon strong coupling in a CuBr bulk microcavity that consists of a CuBr active layer with an effective thickness of λ/2 and HfO/SiOdistributed Bragg reflectors: λ corresponds to an effective resonant wavelength of the lowest-lying exciton. The CuBr crystal has three excitons labeled Z, Z, and Zat the Γ point, where the Zexciton originates from a triplet state, which is peculiar to CuBr. Angle-resolved reflectance spectra measured at 10 K demonstrate the strong coupling behavior of the Z, Z, and Zexcitons and cavity photon, resulting in the formation of four cavity-polariton branches. Analyzing the cavity-polariton dispersion relations based on a phenomenological Hamiltonian for the strong coupling, we evaluated the vacuum Rabi-splitting energies of the Z, Z, and Zexcitons to be 31, 108, and 84 meV, respectively. These Rabi-splitting energies reflect the magnitudes of the oscillator strengths of the relevant excitons. Furthermore, we precisely measured angle-resolved photoluminescence (PL) spectra of the lower polariton branch under a weak excitation condition. In the bottleneck region, the population of the cavity polaritons is negligible, and the PL intensity at= 0 is the highest. These facts suggest that the relaxation process of the cavity polaritons is not affected by a bottleneck effect.