Abstract-Broadband all-electronically tunable MEMS terahertz quantum cascade lasers

Ningren Han, Alexander de Geofroy, David P. Burghoff, Chun Wang I. Chan, Alan Wei Min Lee, John L. Reno, and Qing Hu  »View Author 

Optics Letters, Vol. 39, Issue 12, pp. 3480-3483 (2014)
http://dx.doi.org/10.1364/OL.39.003480

http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-39-12-3480

In this work, we demonstrate all-electronically tunable terahertz quantum cascade lasers (THz QCLs) with MEMS tuner structures. A two-stage MEMS tuner device is fabricated by a commercial open-foundry process performed by the company MEMSCAP. This provides an inexpensive, rapid, and reliable approach for MEMS tuner fabrication for THz QCLs with a high-precision alignment scheme. In order to electronically actuate the MEMS tuner device, an open-loop cryogenic piezo nanopositioning stage is integrated with the device chip. Our experimental result shows that at least 240 GHz of single-mode continuous electronic tuning can be achieved in cryogenic environments (∼4  K) without mode hopping. This provides an important step toward realizing turn-key bench-top tunable THz coherent sources for spectroscopic and coherent tomography applications.

© 2014 Optical Society of America

Abstract-Terahertz laser frequency combs

David Burghoff, Tsung-Yu Kao, Ningren Han, Chun Wang Ivan Chan, Xiaowei Cai, Yang Yang, Darren J. Hayton, Jian-Rong Gao, John L. Reno, Qing Hu

Nature Photonics

(2014)

doi:10.1038/nphoton.2014.85

Received

 

28 January 2014 

Accepted

 

28 March 2014 

Published online

 

11 May 2014

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• http://www.nature.com/nphoton/journal/vaop/ncurrent/abs/nphoton.2014.85.html

Terahertz light can be used to identify numerous complex molecules, but has traditionally remained unexploited due to the lack of powerful broadband sources. Pulsed lasers can be used to generate broadband radiation, but such sources are bulky and produce only microwatts of average power. Conversely, although terahertz quantum cascade lasers are compact semiconductor sources of high-power terahertz radiation, their narrowband emission makes them unsuitable for complex spectroscopy. In this work, we demonstrate frequency combs based on terahertz quantum cascade lasers, which combine the high power of lasers with the broadband capabilities of pulsed sources. By fully exploiting the quantum-mechanically broadened gain spectrum available to these lasers, we can generate 5 mW of terahertz power spread across 70 laser lines. This radiation is sufficiently powerful to be detected by Schottky-diode mixers, and will lead to compact terahertz spectrometers.