GaAs/AlGaAs量子级联激光器自脉动动力学

利用步进扫描时间分辨傅里叶变换红外光谱,研究了波长9.76μm GaAs/AlGaAs量子级联激光器的准连续波激射谱.在驱动电流周期内,时间上堆叠的发射谱能够观察到明显的光强自脉动现象.有源区中的自加热积累大大影响了电子的驰豫和输运性质.热引起的在注入区较高子能级中占据的载流子由于这些子能级与下一注入区的连续态形成共振条件而泄露,而耦合阱有源区中第四子能级的存在加快了这个过程.周期性破坏和恢复的共振条件所引起的载流子泄露在很大程度上导致了时域堆叠光谱的自脉动.

Self-Pulsation Dynamics in GaAs/AlGaAs Quantum Cascade Lasers

Quasi-continuous wave lasing spectra of GaAs/AlGaAs quantum cascade lasers emitting at 9.76μm are characterized by step-scan time-resolved Fourier transform infrared spectroscopy. Pronounced self-pulsation in stacked emission spectra is observed in the driving current duration. Self-heating accumulation in the active region affects the electron relaxation and transport greatly. Thermally-induced carrier occupation of the higher sublevels in an injector can leak out through a resonant condition with the continuum states above the next injector,which will be facilitated by the fourth sublevel of the coupled quantum wells active region. The leaking process arising from the periodic breaking and recovering of resonant tunneling accounts for the physical mechanism of the selfpulsed effect in stacked emission spectra.