TY - GEN
T1 - Long-wavelength (λ ≈ 12- 16 μm) and cascaded transition quantum cascade lasers
AU - Huang, Xue
AU - Chiu, Yenting
AU - Zhang, Jingyuan L.
AU - Charles, William O.
AU - Tokranov, Vadim E.
AU - Oktyabrsky, Serge
AU - Gmachl, Claire F.
PY - 2013/6/3
Y1 - 2013/6/3
N2 - Long-wavelength (12 - 16 μm) Quantum Cascade (QC) lasers are crucial devices for improving the detection sensitivity of QC-laser based sensing for important gases including BTEX (benzene, toluene, ethylbenzene, and xylenes) or uranium hexafluoride. A high-performance QC laser emitting at ∼ 14 μm is reviewed, optimized by employing a diagonal optical transition and a two-phonon-continuum depletion scheme. It shows a low threshold current density of 2.0 kA/cm2, a peak power of 336 mW, all at 300 K, as well as a high characteristic temperature ∼ 310 K over a wide temperature range around room temperature (240- 390 K). Single-mode operation is demonstrated with short cavities, with a mode-hop-free continuous tuning range of ∼ 5.5 cm-1. The ridge-width dependence of threshold of ∼ 14 μm QC lasers by both wet etching and dry etching is studied. The main challenge for narrowing wet-etched ridges is the high loss caused by mode coupling to surface plasmon modes at the insulator/metal interface of sloped sidewalls. Conversely, dryetched ridges avoid surface plasmon mode coupling due to the absence of transverse magnetic polarization for the vertical insulator and metal layers. To further improve the efficiency of QC lasers, a same-wavelength cascaded transition approach is developed, with two sequential cascaded transitions at the same wavelength ∼ 14.2 μm in each stage. This same-wavelength cascaded-transition QC gain medium was inserted between two conventional QC stacks at the same wavelength. Slope efficiency is increased by 46% when laser operation changes from the single-transition region to the cascaded-transition region.
AB - Long-wavelength (12 - 16 μm) Quantum Cascade (QC) lasers are crucial devices for improving the detection sensitivity of QC-laser based sensing for important gases including BTEX (benzene, toluene, ethylbenzene, and xylenes) or uranium hexafluoride. A high-performance QC laser emitting at ∼ 14 μm is reviewed, optimized by employing a diagonal optical transition and a two-phonon-continuum depletion scheme. It shows a low threshold current density of 2.0 kA/cm2, a peak power of 336 mW, all at 300 K, as well as a high characteristic temperature ∼ 310 K over a wide temperature range around room temperature (240- 390 K). Single-mode operation is demonstrated with short cavities, with a mode-hop-free continuous tuning range of ∼ 5.5 cm-1. The ridge-width dependence of threshold of ∼ 14 μm QC lasers by both wet etching and dry etching is studied. The main challenge for narrowing wet-etched ridges is the high loss caused by mode coupling to surface plasmon modes at the insulator/metal interface of sloped sidewalls. Conversely, dryetched ridges avoid surface plasmon mode coupling due to the absence of transverse magnetic polarization for the vertical insulator and metal layers. To further improve the efficiency of QC lasers, a same-wavelength cascaded transition approach is developed, with two sequential cascaded transitions at the same wavelength ∼ 14.2 μm in each stage. This same-wavelength cascaded-transition QC gain medium was inserted between two conventional QC stacks at the same wavelength. Slope efficiency is increased by 46% when laser operation changes from the single-transition region to the cascaded-transition region.
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U2 - 10.1117/12.2002246
DO - 10.1117/12.2002246
M3 - Conference contribution
AN - SCOPUS:84878303787
SN - 9780819494092
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Novel In-Plane Semiconductor Lasers XII
T2 - Novel In-Plane Semiconductor Lasers XII
Y2 - 4 February 2013 through 7 February 2013
ER -