Since its first observation, the polariton lasing threshold in organic films has been anomalously high, given that Bosonic condensation should occur at vanishingly small pumping powers. Here, we investigate the temperature dependence of a polariton laser employing an amorphous organic thin film, 2,7-bis[9,9-di(4-methylphenyl)-fluoren-2-yl]-9,9-di(4-methylphenyl)fluorene, in a vertical optical microcavity. An increase in laser threshold is observed at temperatures <45 K, while the threshold remains unchanged as the temperature increases up to room temperature. In contrast, the energy dispersion characteristic of cavity polaritons is independent of temperature. At low temperature, an energy relaxation bottleneck along the polariton dispersion takes place below threshold. The bottleneck is found to be responsible for the anomalous increase in threshold with decreasing temperature. As the pumping power increases, amplified spontaneous emission (ASE) is observed prior to the onset of lasing. We also study the photoluminescence of the neat organic film versus temperature to explain the origin of the bottleneck in the exciton polariton dispersion.

中文翻译：

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非晶有机薄膜极化激光的温度依赖性

自从首次观察以来，有机硅的极化激射阈值一直异常高，因为玻色子凝结应该在消失的很小的泵浦功率下发生。在这里，我们研究使用非晶有机薄膜2,7-双[9,9-二（4-甲基苯基）-芴-2-基] -9,9-二（4-）的极化子激光器的温度依赖性。垂直光学微腔中的甲基苯基）芴。在<45 K的温度下观察到激光阈值增加，而阈值随着温度升高到室温而保持不变。相反，腔极化子的能量色散特性与温度无关。在低温下，沿着极化子色散的能量弛豫瓶颈发生在阈值以下。发现瓶颈是阈值随温度降低而异常增加的原因。随着泵浦功率的增加，在发射激光之前会观察到自发发射放大（ASE）。我们还研究了纯有机膜的光致发光与温度的关系，以解释激子极化子分散体中瓶颈的起源。