Linear-Polarization Optical Property of CdSe Quantum Rods

The linear-polarization optical property of CdSe quantum rods is studied in the framework of effectivemass envelope function theory. The effects of shape and magnetic field on the linear polarization factors are investigated. It is found that CdSe quantum spheres have negative polarization factors （xy-polarized emission）and quantum long rods with small radius have positive linear polarization factors （z-polarized emission）. The z-direction is the direction of the c axis. Quantum long rods with large radius have negative linear polarization factors,due to the hexagonal crystal symmetry and the crystal field splitting energy. The linear polarization factors decrease and may change from a positive value to a negative value;i, e. ,the z-polarized emissions decrease relative to xy-polarized emissions as the magnetic field applied along the z direction increases.

保偏光纤转轴熔接Sagnac干涉环的光学游标效应及温度传感器

为了实现高灵敏度的温度传感,通过在基于保偏光纤Sagnac干涉仪的Sagnac环内增加一段保偏光纤,控制两段保偏光纤快轴熔接角度接近45°,设计并制造了保偏光纤转轴熔接Sagnac干涉环结构。在理论上通过Jones矩阵推导了保偏光纤转轴熔接Sagnac干涉环的干涉谱公式,基于仿真分析研究了主要参数对保偏光纤转轴熔接Sagnac干涉环输出特性的影响。仿真结果表明,保偏光纤转轴熔接Sagnac干涉环实现了光学游标效应,两段保偏光纤的平均长度、两段保偏光纤的长度差分别影响保偏光纤转轴熔接Sagnac干涉环输出干涉谱的波长间隔和包络周期;在实验中,将保偏光纤转轴熔接Sagnac干涉环应用在光纤温度传感器中。实验结果表明,在2cm的感温区域,保偏光纤转轴熔接Sagnac干涉环温度传感器的灵敏度就达到了-2.44nm/℃,是普通Sagnac干涉环温度传感器(-0.163nm/℃)的14.97倍。