影响AlGaN/GaN量子级联激光器性能的因素研究

在已有理论基础之上,采用严格的计算方法对激光器实现太赫兹(THz)波的辐射进行了可能性分析。利用传递矩阵法,通过Matlab软件计算了基于AlGaN/GaN材料体系的三能级量子级联激光器导带子能级与电子波函数的分布,详细分析了由该材料特有的极化效应所产生的极化场,得出了在近共振条件下偶极跃迁元、外加电场、垒层Al组分及导带子能级能级差之间的关系,并研究了它们对激光器性能的影响。分析结果表明,实现受激辐射的条件非常严格,Al组分取0.15或0.16时较为适宜,同时外加电场需大于63kV/cm,但不能过大,这样才能满足近共振条件,实现粒子数反转达到太赫兹量子级联激射。在Al组分为0.15,外加电场为69.0kV/cm时激光器的偶极跃迁元最大,表明跃迁几率也最大,对激光器的性能有利,可以为量子级联激光器构造较好的有源区。

Study of the Factors Influencing the Properties of AlGaN/GaN Quantum Cascade Lasers

Based on the predecessor′s theoretical achievements, probabilistic analysis for realizing terahertz (THz) radiation of lasers by strict calculation method is given. The distributions of conduction subband structure and the electron wave function of GaN-based three-level quantum cascade lasers are solved with the transfer matrix method by Matlab, the polarization field of material is analyzed detailedly. The relationships among dipole matrix element, applied external electric field, the barrier layer of Al composition and energy difference of conduction subband in near-resonant conditions are calculated, and their effects on properties of lasers are studied. The analysis of the results shows that realizing stimulated radiation is very strict, it is proper that the composition of Al is 0.15 or 0.16, and the external electric field intensity is greater than 63 kV/cm，but is not too large. In this case, the near-resonant conditions can be satisfied, so that population inversion is realized to reach THz quantum cascade lasing. While the largest dipole matrix element is obtained at the composition of Al of 0.15 and the external electric field intensity of 69.0 kV/cm, indicating that transition probability is also the largest. It is beneficial for the properties of lasers, thus the preferable active region can be constructed for quantum cascade lasers.