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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, 13:51 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.