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16 February 2011 The temperature dependence of key electro-optical characteristics for mid-infrared emitting quantum cascade lasers
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Proceedings Volume 7953, Novel In-Plane Semiconductor Lasers X; 79530N (2011)
Event: SPIE OPTO, 2011, San Francisco, California, United States
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.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Dan Botez, Jae Cheol Shin, Sushil Kumar, Jeremy Kirch, Chun-Chieh Chang, Luke J. Mawst, Igor Vurgaftman, Jerry R. Meyer, Alfredo Bismuto, Borislav Hinkov, and Jerome Faist "The temperature dependence of key electro-optical characteristics for mid-infrared emitting quantum cascade lasers", Proc. SPIE 7953, Novel In-Plane Semiconductor Lasers X, 79530N (16 February 2011);


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