Abstract-Surface-emitting terahertz quantum cascade lasers with continuous-wave power in the tens of milliwatt range

Gangyi Xu^1,2,a), Lianhe Li³, Nathalie Isac¹, Yacine Halioua¹, A. Giles Davies³,
Edmund H. Linfield³ and Raffaele Colombelli^1,b)
 HIDE AFFILIATIONS
1 Institut d'Electronique Fondamentale, Univ. Paris Sud, UMR8622 CNRS, 91405 Orsay, France
2 Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
3 School of Electronic and Electrical Engineering, University of Leeds, Leeds LS9 2JT, United Kingdom
a) E-mail: gangyi.xu@mail.sitp.ac.cn
b) E-mail: raffaele.colombelli@u-psud.fr
Appl. Phys. Lett. 104, 091112 (2014); http://dx.doi.org/10.1063/1.48666612
http://scitation.aip.org/content/aip/journal/apl/104/9/10.1063/1.4866661

We demonstrate efficient surface-emitting terahertz frequency quantum cascade lasers with continuous wave output powers of 20–25 mW at 15 K and maximum operating temperatures of 80–85 K. The devices employ a resonant-phonon depopulation active region design with injector, and surface emission is realized using resonators based on graded photonicheterostructures (GPHs). GPHs can be regarded as energy wells for photons and have recently been implemented through grading the period of the photonic structure. In this paper, we show that it is possible to keep the period constant and grade instead the lateral metal coverage across the GPH. This strategy ensures spectrally single-mode operation across the whole laser dynamic range and represents an additional degree of freedom in the design of confining potentials for photons.

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