P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow, Russia.
J Phys Condens Matter. 2011 Jun 1;23(21):215302. doi: 10.1088/0953-8984/23/21/215302. Epub 2011 May 9.
The emission dynamics of a GaAs microcavity at different angles of observation with respect to the sample normal under conditions of nonresonant picosecond-pulse excitation is measured. At sufficiently high excitation densities, the decay time of the lower polariton emission increases with the polariton wavevector; at low excitation densities the decay time is independent of the wavevector. The effect of additional nonresonant continuous illumination on the emission originating from the bottom of the lower polariton branch is investigated. The additional illumination leads to a substantial increase in the emission intensity (considerably larger than the intensity of the photoluminescence excited by this illumination alone). This fact is explained in terms of acceleration of the polariton relaxation to the radiative states due to scattering by charge carriers created by the additional illumination. The results obtained show that, at large negative detunings between the photon and exciton modes, polariton-polariton and polariton-free carrier scattering are the main processes responsible for the filling of states near the bottom of the lower polariton branch.
在非共振皮秒脉冲激发下，测量了相对于样品法线以不同角度观察的 GaAs 微腔的发射动力学。在足够高的激发密度下，下极化激元发射的衰减时间随极化激元波矢增加而增加；在低激发密度下，衰减时间与波矢无关。研究了额外的非共振连续照明对源自下极化激元支底部的发射的影响。附加照明导致发射强度的大幅增加（比仅由该照明激发的光致发光强度大得多）。这一事实可以用由于额外照明产生的载流子散射导致极化激元弛豫到辐射态的加速来解释。所得到的结果表明，在光子和激子模式之间存在大的负失谐时，极化激元-极化激元散射和极化激元-自由载流子散射是填充下极化激元支底部附近态的主要过程。
