Abstract-Thermoelectric-cooled terahertz quantum cascade lasers

Martin A. Kainz, Mykhaylo P. Semtsiv, Georgios Tsianos, Sergii Kurlov, W. Ted Masselink, Sebastian Schönhuber, Hermann Detz, Werner Schrenk, Karl Unterrainer, Gottfried Strasser, and Aaron M. Andrews

Fig. 3 THz QCL performance cooled with the thermoelectric cooler. (a) Light-current behaviour in pulsed mode and an operating temperature of 171 K (TEC input: 15 A, 32.1 V). (b) Pulsed and average power of the QCL at different duty cycles. A maximum average power of 120 μW is reached at a duty cycle of 5%.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-15-20688

We demonstrate the first lasing emission of a thermo-electrically cooled terahertz quantum cascade laser (THz QCL). A high temperature three-well THz QCL emitting at 3.8 THz is mounted to a novel five-stage thermoelectric cooler reaching a temperature difference of ΔT = 124 K. The temperature and time-dependent laser performance is investigated and shows a peak pulse power of 4.4 mW and a peak average output power of 100 μW for steady-state operation.

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Abstract-Spectrally resolved far-fields of terahertz quantum cascade lasers

Martin Brandstetter, Sebastian Schönhuber, Michael Krall, Martin A. Kainz, Hermann Detz, Tobias Zederbauer, Aaron M. Andrews, Gottfried Strasser, Karl Unterrainer

(Submitted on 18 Aug 2016)

https://arxiv.org/abs/1608.05257

We demonstrate a convenient and fast method to measure the spectrally resolved far-fields of multimode terahertz quantum cascade lasers by combining a microbolometer focal plane array with an FTIR spectrometer. Far-fields of fundamental TM0 and higher lateral order TM1 modes of multimode Fabry-P\'erot type lasers have been distinguished, which very well fit to the results obtained by a 3D finite-element simulation. Furthermore, multimode random laser cavities have been investigated, analyzing the contribution of each single laser mode to the total far-field. The presented method is thus an important tool to gain in-depth knowledge of the emission properties of multimode laser cavities at terahertz frequencies, which become increasingly important for future sensing applications.

Abstract-Coupled cavity terahertz quantum cascade lasers with integrated emission monitoring

Coupled cavity terahertz quantum cascade lasers with integrated emission monitoring Michael Krall, Michael Martl, Dominic Bachmann, Christoph Deutsch, Aaron M. Andrews, Werner Schrenk, Gottfried Strasser, and Karl Unterrainer  »View Author Affiliations

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-23-3-3581

Optics Express, Vol. 23, Issue 3, pp. 3581-3588 (2015)
http://dx.doi.org/10.1364/OE.23.003581

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We demonstrate the on-chip generation and detection of terahertz radiation in coupled cavity systems using a single semiconductor heterostructure. Multiple sections of a terahertz quantum cascade laser structure in a double-metal waveguide are optically coupled and operate either as a laser or an integrated emission monitor. A detailed analysis of the photon-assisted carrier transport in the active region below threshold reveals the detection mechanism for photons emitted by the very same structure above threshold. Configurations with a single laser cavity and two coupled laser cavities are studied. It is shown that the integrated detector can be used for spatial sensing of the light intensity within a coupled cavity.

© 2015 Optical Society of America

Abstract-Influence of the facet type on the performance of terahertz quantum cascade lasers with double-metal waveguides

Werner Schrenk², Gottfried Strasser²,  Karl Unterrainer¹
Martin Brandstetter¹, Michael Krall¹, Christoph Deutsch¹, Hermann Detz², Aaron M. Andrews²,

¹Photonics Institute and Center for Micro- and Nanostructures, Vienna University of Technology, Gusshausstrasse 29, A-1040 Vienna, Austria
²Institute of Solid-State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Floragasse 7, A-1040 Vienna, Austria 

http://apl.aip.org/resource/1/applab/v102/i23/p231121_s1?isAuthorized=no

We investigate the influence of cleaved and dry chemically etched facets on the performance of terahertz quantum cascade lasers with double-metal waveguides. We theoretically show that the reflectivity and therefore also the mirror losses depend on the facet type. We fabricated devices employing both a cleaved and an etched facet, which show an asymmetric output characteristic. Furthermore, we compare the performance in terms of maximum operation temperature of lasers with each facet configuration. The results suggest that the devices are operated in a mirror loss dominated regime.

© 2013 © 2013 Author(s).