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-Enhanced Crystal Quality of AlxIn1-xAsySb1-y for Terahertz Quantum Cascade Lasers

Tobias Zederbauer 1,* , Aaron Maxwell Andrews 1

, Donald MacFarland 1

, Hermann Detz 2

,Werner Schrenk 3

 and Gottfried Strasser 1,3

1 TU Wien, Institude of Solid State Electronics, Floragasse 7, 1040 Wien, Austria2 Austrian Academy of Sciences, Dr. Ignaz Seipel-Platz 2, 1010 Wien, Austria3 TU Wien, Center for Micro and Nano Structures, Floragasse 7, 1040 Wien, Austria

* Author to whom correspondence should be addressed.

Received: 31 March 2016 / Revised: 14 April 2016 / Accepted: 15 April 2016 / Published: 20 April 2016

(This article belongs to the Special Issue Quantum Cascade Lasers - Advances and New Applications)

http://www.mdpi.com/2304-6732/3/2/20

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This work provides a detailed study on the growth of AlxIn1-xAsySb1-y lattice-matched to InAs by Molecular Beam Epitaxy. In order to find the conditions which lead to high crystal quality deep within the miscibility gap, AlxIn1-xAsySb1-y with x = 0.462 was grown at different growth temperatures as well as As2 and Sb2 beam equivalent pressures. The crystal quality of the grown layers was examined by high-resolution X-ray diffraction and atomic force microscopy. It was found that the incorporation of Sb into Al0.462In0.538AsySb1-y is strongly temperature-dependent and reduced growth temperatures are necessary in order to achieve significant Sb mole fractions in the grown layers. At 480 ∘C$$ lattice matching to InAs could not be achieved. At 410 ∘C$$ lattice matching was possible and high quality films of Al0.462In0.538AsySb1-y were obtained.

Abstract-InAs based terahertz quantum cascade lasers

Martin Brandstetter^1,a), Martin A. Kainz¹, Tobias Zederbauer²,Michael Krall¹, Sebastian Schönhuber¹, Hermann Detz³, Werner Schrenk², Aaron Maxwell Andrews², Gottfried Strasser² and Karl Unterrainer¹
 HIDE AFFILIATIONS
1 Photonics Institute and Center for Micro- and Nanostructures, Technische Universität Wien, Gusshausstrasse 27-29, 1040 Vienna, Austria
2 Institute for Solid State Electronics and Center for Micro- and Nanostructures, Technische Universität Wien, Floragasse 7, 1040 Vienna, Austria
3 Austrian Academy of Sciences, Dr. Ignaz Seipel-Platz 2, 1010 Vienna, Austria
a) Electronic mail: martin.brandstetter@tuwien.ac.at
Appl. Phys. Lett. 108, 011109 (2016); http://dx.doi.org/10.1063/1.4939551

http://scitation.aip.org/content/aip/journal/apl/108/1/10.1063/1.4939551?TRACK=RSS

We demonstrate terahertz lasing emission from a quantum cascade structure, realized with InAs/AlAs0.16Sb0.84heterostructures. Due to the lower effective electron mass, InAs based active regions are expected to provide a higher optical gain compared to structures consisting of GaAsor InGaAs. The growth by molecular beam epitaxy enabled the fabrication of monolayer-thick barriers, required for the active region, which is based on a 3-well resonantphonon depletion design. Devices were processed in a double-metal waveguide geometry to ensure high mode confinement and low optical losses. Lasing emission at 3.8 THz was observed at liquid helium temperatures by applying a magnetic field perpendicular to the layered structure in order to suppress parasitic scattering channels. These results demonstrate the feasibility of InAs based active regions for terahertz quantum cascade lasers, potentially enabling higher operating temperatures.

Abstract-Magnetic-field assisted performance of InGaAs/GaAsSb terahertz quantum cascade lasers

Simon Maëro¹, Louis-Anne de Vaulchier¹, Yves Guldner¹,Christoph Deutsch², Michael Krall², Tobias Zederbauer³,Gottfried Strasser³, and Karl Unterrainer^{2
http://apl.aip.org/resource/1/applab/v103/i5/p051116_s1?isAuthorized=no&}

We report on a magnetic-field investigation of a In_0.53Ga_0.47As/GaAs_0.51Sb_0.49terahertz quantum cascade laser. Owing to the suppression of inter-Landau level non-radiative scattering, the device performances are strongly improved at high magnetic field. Working temperature up to 190 K and current threshold of 450 A/cm² are measured at 11 T, comparable to the state-of-the-art GaAs/AlGaAs terahertz lasers. The nominally symmetric three-well structure presents significantly better performance with negative bias polarisation because of the inverted-interface roughness impact on the laser action.

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