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Proceedings Paper

The temperature dependence of key electro-optical characteristics for mid-infrared emitting quantum cascade lasers
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Paper Abstract

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.

Paper Details

Date Published: 16 February 2011
PDF: 12 pages
Proc. SPIE 7953, Novel In-Plane Semiconductor Lasers X, 79530N (16 February 2011); doi: 10.1117/12.874197
Show Author Affiliations
Dan Botez, Univ. of Wisconsin-Madison (United States)
Jae Cheol Shin, Univ. of Wisconsin-Madison (United States)
Sushil Kumar, Lehigh Univ. (United States)
Jeremy Kirch, Univ. of Wisconsin-Madison (United States)
Chun-Chieh Chang, Univ. of Wisconsin-Madison (United States)
Luke J. Mawst, Univ. of Wisconsin-Madison (United States)
Igor Vurgaftman, U.S. Naval Research Lab. (United States)
Jerry R. Meyer, U.S. Naval Research Lab. (United States)
Alfredo Bismuto, ETH Zurich (Switzerland)
Borislav Hinkov, ETH Zurich (Switzerland)
Jerome Faist, ETH Zurich (Switzerland)

Published in SPIE Proceedings Vol. 7953:
Novel In-Plane Semiconductor Lasers X
Alexey A. Belyanin; Peter M. Smowton, Editor(s)

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