ZnSe/BeTe量子阱中激子的光学二次和三次谐波产生
Optical second and third harmonic generation on excitons in ZnSe/BeTe quantum wells
摘要：
在ZnSe/BeTe量子阱中发现了激子的光学谐波产生，具有II型能带排列。两种实验方法与光谱宽飞秒激光脉冲和光谱窄皮秒脉冲用于光谱研究，通过二次和三次谐波产生（SHG和THG）。SHG信号对于沿着结构的生长轴（其为[001]晶体轴）的光传播是被禁止的，但是可以由外部磁场感生。在零磁场下检测到THG信号，并且其强度与场无关。一组理论分析的SHG和THG旋转各向异性图，使我们能够确定所涉及的激发机制。
英文摘要：
Optical harmonic generation on excitons is found in ZnSe/BeTe quantum wells with type-II band alignment. Two experimental approaches with spectrally-broad femtosecond laser pulses and spectrally-narrow picosecond pulses are used for spectroscopic studies by means of second and third harmonic generation (SHG and THG). The SHG signal is symmetry-forbidden for light propagation along the structure's growth axis, which is the [001] crystal axis, but can be induced by an external magnetic field. The THG signal is detected at zero magnetic field and its intensity is field independent. A group theory analysis of SHG and THG rotational anisotropy diagrams allows us to identify the involved excitation mechanisms.
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