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Far-Infrared Quantum Cascade Lasers Operating in the AlAs Phonon Reststrahlen Band

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journal contribution
posted on 12.12.2016 by Keita Ohtani, Mattias Beck, Martin Josef Süess, Jérôme Faist, Aaron Maxwell Andrews, Tobias Zederbauer, Hermann Detz, Werner Schrenk, Gottfried Strasser
We report on the operation of a double metal waveguide far-infrared quantum cascade laser emitting at 28 μm, corresponding to the AlAs-like phonon reststrahlen band. To avoid absorption by AlAs-like optical phonons, the Al-free group V alloy GaAs0.51Sb0.49 is used as a barrier layer in the bound-to-continuum-based active region. Lasing occurs at a wavelength of 28.3 μm, which is the longest wavelength among the quantum cascade lasers operating from mid-infrared to far-infrared. The threshold current density at 50 K is 5.5 kA/cm2, and maximum operation temperature is 175 K. We also discuss the feasibility that the operation wavelength can cover the whole spectral range bridging between mid-infrared and terahertz by choosing properly suited group III–V materials.