光抽运下1300nm自旋垂直腔面发射激光器输出激光的圆偏振转换及偏振双稳特性

Circular Polarization Switching and Polarization Bistability of Optically Pumped 1300 nm Spin Vertical-Cavity Surface-Emitting Lasers

基于自旋反转模型,数值研究了光抽运下1300nm自旋垂直腔面发射激光器(Spin-VCSEL)输出激光的圆偏振转换(PS)及偏振双稳(PB)特性。研究结果表明:对于一定的抽运光偏振椭圆率PP,抽运光功率能在一定程度上控制激光器输出光的偏振椭圆率Pout,其绝对值随抽运光功率的增加而逐渐增大;对于一定的归一化抽运光功率η,采用正向扫描(逐渐增加)和反向扫描(逐渐减小)PP时,Spin-VCSEL输出的左旋圆偏振光与右旋圆偏振光之间会发生PS,并可观察到PB现象。对于较小的η,双稳环宽度随η的增加先增加到一个最大值然后减小到0;对于较大的η,双稳环宽度随η的增加总体上呈现出逐渐减小的趋势。激光器的线宽增强因子α和有源区介质的双折射系数γp等内部参数对由PP变化引起的PS和PB均有较大的影响。此外,确定了双稳环宽度在某些激光器关键内部参数和η构成的参数空间中的分布图。

Based on the spin-flip model,the output laser circular polarization switching（PS）and polarization bistability（PB）characteristics of 1300 nm spin vertical-cavity surface-emitting lasers（Spin-VCSEL）under optical pumping are investigated numerically.The results show that,for a certain polarization ellipticity PPof the pump light,the pump power Poutcan control the polarization ellipticity of the output light at a certain extent,and its absolute value increases with the increase of pump power.For a certain normalized pump powerη,the PS can occur between the left circularly polarized light and the right circularly polarized light of the spin-VCSEL and the PB phenomenon can be observed when PPis scanned forward（gradually increasing）or backward（gradually decreasing）.For the smallη,the bistability loop width increases to a maximum,and then decreases to 0 with the increasingη.For a largeη,the bistability loop width shows a decreasing trend with the increasingηon the whole.Moreover,the internal parameters such as linewidth enhancement factorαof the laser and birefringence coefficientγpof the source medium have a great influence on the PS and PB characteristics induced through the changing of PP.In addition,the distribution of the bistability loop width is also given in the parameter space of some key internal parameters of the laser andη.