TY - GEN
T1 - The temperature dependence of key electro-optical characteristics for mid-infrared emitting quantum cascade lasers
AU - Botez, Dan
AU - Shin, Jae Cheol
AU - Kumar, Sushil
AU - Kirch, Jeremy
AU - Chang, Chun Chieh
AU - Mawst, Luke J.
AU - Vurgaftman, Igor
AU - Meyer, Jerry R.
AU - Bismuto, Alfredo
AU - Hinkov, Borislav
AU - Faist, Jerome
PY - 2011
Y1 - 2011
N2 - The equations for the threshold-current density Jth, differential quantum efficiency ?d 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 T 1 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,maxis 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 °C heatsink-temperature range.
AB - The equations for the threshold-current density Jth, differential quantum efficiency ?d 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 T 1 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,maxis 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 °C heatsink-temperature range.
KW - Electron leakage
KW - Mid-infrared
KW - Quantum cascade lasers
KW - Slope-efficiency characteristic temperature
KW - Strain-compensated
KW - Tapered active region
KW - Threshold-current characteristic temperature
KW - Wallplug efficiency
UR - http://www.scopus.com/inward/record.url?scp=79953077256&partnerID=8YFLogxK
U2 - 10.1117/12.874197
DO - 10.1117/12.874197
M3 - Conference contribution
AN - SCOPUS:79953077256
SN - 9780819484901
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Novel In-Plane Semiconductor Lasers X
T2 - Novel In-Plane Semiconductor Lasers X
Y2 - 25 January 2011 through 28 January 2011
ER -