基于电子自旋弛豫全光开关中的瞬态特性

Transient Characteristics in All-Optical Switching Using Electron Spin Relaxation

设计了基于电子自旋弛豫的透射式全光开关模型,该光开关具有开关时间短、结构简单、光学非线性强等特点。研究在右旋圆偏振光抽运下GaAs/AlGaAs半导体多量子阱(MQWs)中以相空间填充(PSF)和库仑屏蔽(CS)为主要因素导致的激子吸收饱和行为,计算与抽运光同向(探测光与抽运光的圆偏振方向相同)和反向(探测光与抽运光的圆偏振方向相反)的圆偏振探测光吸收系数的变化,得到两种圆偏振光差分透射率改变量随延迟时间的变化。实验采用飞秒抽运-探测技术,获得了室温下GaAs/AlGaAs多量子阱同向圆偏振探测光的透射曲线,观察到了明显的饱和吸收现象,与数值模拟的结果相符。

An all-optical transmission switching model based on electron spin relaxation was designed, and this new configuration of optical switch grants the features of short switching time, simple structure, and high optical nonlinearities. The exciton saturation caused by phase-space filling （PSF） and Coulomb screening （CS） in GaAs/AIGaAs multiple quantum well was discussed under the right circularly polarized pump beam. The absorption coefficients variations of the circularly polarized probe beam in the same and opposite polarization direction with the pump beam were calculated. The differential transmission change of both polarization as a function of delay time was obtained. The pump-probe experiment was carried out to measure the change curve in transmission of the same circularly polarized states probe beam at room temperature, and obvious saturation phenomenon is observed which agrees with the numerical result.