The ultrafast scattering dynamics of intersubband polaritons in dispersive cavities embedding $\mathrm{GaAs}/\mathrm{AlGaAs}$ quantum wells are studied directly within their band structure using a noncollinear pump-probe geometry with phase-stable midinfrared pulses. Selective excitation of the lower polariton at a frequency of $\sim 25\mathrm{THz}$ and at a finite in-plane momentum $k_{\Vert }$ leads to the emergence of a narrowband maximum in the probe reflectivity at $k_{\Vert }=0$. A quantum mechanical model identifies the underlying microscopic process as stimulated coherent polariton-polariton scattering. These results mark an important milestone toward quantum control and bosonic lasing in custom-tailored polaritonic systems in the mid and far infrared.

中文翻译：

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色散微腔中的子带间极化子-极化子散射

色散腔嵌入中子带间极化子的超快散射动力学$\mathrm{砷化镓}/\mathrm{砷化镓}$使用具有相位稳定的中红外脉冲的非共线泵浦探针几何结构直接在其能带结构内研究量子阱。下极化子的选择性激发频率为$～25\mathrm{太赫兹}$在有限的平面内动量下${ķ}_{\Vert }$导致探针反射率出现窄带最大值${ķ}_{\Vert }=0$. 量子力学模型将潜在的微观过程识别为受激相干极化子-极化子散射。这些结果标志着在中红外和远红外定制极化子系统中实现量子控制和玻色子激光的重要里程碑。