86% internal differential efficiency from 8 to 9 µm-emitting, step-taper active-region quantum cascade lasers.
86% internal differential efficiency from 8 to 9 µm-emitting, step-taper active-region quantum cascade lasers.
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8 至 9 µm 发射、阶梯锥度有源区量子级联激光器的内部微分效率为 86%。
作者：
J. Kirch;Chun;C. Boyle;L. Mawst;D. Lindberg;T. Earles;D. Botez
8.4μ m发射量子级联激光器（QCL）从阈值开始即具有载流子泄漏抑制和类微带载流子提取功能。斜率效率特征温度T1，即载波泄漏抑制的特征，被发现为665 K。共振隧穿载流子从较低的激光能级（II）和低于它的能级提取，与高效的II-去布居耦合，提供了非常短的II寿命（~0.12 ps）。结果表明，激光跃迁微分效率达到89%，由变镜损研究得到的内微分效率η id为86%，与理论值符合得很好。对8.8 μ m发射QCL的研究也提供了86%的η id值。导出了外微分效率的修正公式，使中红外QCL的η id值基本上达到90%。反过来，基本的wallplug效率限制比之前预测的高出约34%。
8.4 μm-emitting quantum cascade lasers (QCLs) have been designed to have, right from threshold, both carrier-leakage suppression and miniband-like carrier extraction. The slope-efficiency characteristic temperature T1, the signature of carrier-leakage suppression, is found to be 665 K. Resonant-tunneling carrier extraction from both the lower laser level (ll) and the level below it, coupled with highly effective ll-depopulation provide a very short ll lifetime (~0.12 ps). As a result the laser-transition differential efficiency reaches 89%, and the internal differential efficiency ηid, derived from a variable mirror-loss study, is found to be 86%, in good agreement with theory. A study of 8.8 μm-emitting QCLs also provides an ηid value of 86%. A corrected equation for the external differential efficiency is derived which leads to a fundamental limit of ~90% for the ηid values of mid-infrared QCLs. In turn, the fundamental wallplug-efficiency limits become ~34% higher than previously predicted.