The temperature dependence of key electro-optical characteristics for mid-infrared emitting quantum cascade lasers
The temperature dependence of key electro-optical characteristics for mid-infrared emitting quantum cascade lasers
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中红外发射量子级联激光器关键电光特性的温度依赖性
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
J. Faist
中科院分区：
文献类型：
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作者：
D. Botez;J. Shin;Sushil Kumar;J. Kirch;Chun;L. Mawst;I. Vurgaftman;J. Meyer;A. Bismuto;B. Hinkov;J. Faist
对量子级联激光器的阈值电流密度Jth、微分量子效率ηd和最大壁塞效率ηwp、max方程进行了修正。我们使用了一个热激发模型，即“热”注入电子从上激光态到上有源区能量态来计算泄漏电流。在常规和深井qcl中，计算得到的第j个特征温度T0与实验结果吻合较好。推导出ηd的特征温度T1是由于电子泄漏和波导损耗系数的增加。对于常规中红外QCLs ηwp，发现max与温度有很强的相关性，这解释了实验数据。通过采用锥形有源区（TA）的新概念，对深井qcl进行了优化，以实现对电子泄漏电流的虚拟抑制。在室温下，对于连续波（CW）工作，发射4.5-5.0 μm的TA qcl，我们估计阈值电流降低了~ 25%，活性区温度在ηwp，最大值处升高了~ 30%，单端ηwp，最大值至少降低了22%。TA qcl的初步结果包括在20-60℃的散热器温度范围内T1值高达454 K。
The equations for the threshold-current density Jth, differential quantum efficiency ηd and maximum wallplug efficiency ηwp,max for quantum-cascade lasers (QCLs) have been modified for electron leakage and backfilling. We used a thermalexcitation model of "hot" injected electrons from the upper laser state to upper active-region energy states to calculate leakage currents. Then the calculated characteristic temperature T0 for Jth was found to agree well with experiment for both conventional and deep-well QCLs. The characteristic temperature T1 for ηd was deduced to be due to both electron leakage and an increase in the waveguide-loss coefficient. For conventional mid-infrared QCLs ηwp,max is found to be strongly temperature dependent which explains experimental data. By using a new concept: tapered active-region (TA), deep-well QCLs have been optimized for virtual suppression of the electron-leakage currents. In turn, at room temperature, for continuous-wave (CW)-operating, 4.5-5.0 μm-emitting TA QCLs we estimate the threshold current to decrease by ~ 25 %, the active-region temperature rise at the ηwp,max point to decrease by ~ 30 %, and the single-ended, ηwp,max value to become at least 22 %. Preliminary results from TA QCLs include T1 values as high as 454 K, over the 20-60 oC heatsink-temperature range.