All of you interested in physics are cordially invited!

Physikalisches Kolloquium

Prof. Dr. Jérôme Faist, ETH Zürich, Schweiz:

Terahertz quantum cascade lasers: from single

mode operation to frequency combs

Thursday, 10.11.2016, 17:15, HS 100

Reception with coffee & cookies 16:45

Abstract

The quantum cascade laser[1] has demonstrated the ability to provide gain over a very broad wavelength range, and has seen its

operation wavelength extended to the THz almost 15 years ago[2]. These devices have demonstrated very unique properties in

for high-power and single mode operation, very relevant for applications such as local oscillator sources for radio-astronomy.

These devices take advantage of design features both available in the optical and microwave domain such as extractor antenna

or third-order DFB extractors. We will report on devices that can produce single mode with a very accurate and predictable

frequency and in which the light is coupled out via an array of patch antenna.

We will also focus on recent developments including the demonstration of THz optical frequency combs[3] [4] based on QCL

active regions. The active regions of these devices can extend their gain to more than an octave of bandwidth[4], opening the

possibility of self-referencing and dual-comb spectrosocpy. Recent advances include dual-comb on a single chip, new insights on

the role of dispersion for the comb control, as well as on the possibility of generating very short pulses.

[1] J. Faist, Quantum cascade lasers, 1st ed.: Oxford University Press, 2013.

[2] R. Kohler, A. Tredicucci, F. Beltram, H. Beere, E. Linfield, A. Davies, et al., "Terahertz semiconductor-heterostructure laser," in

Nature vol. 417, ed, 2002, pp. 156-159.

[3] D. Burghoff, T.-Y. Kao, N. Han, C. W. I. Chan, X. Cai, Y. Yang, et al., "Terahertz laser frequency combs," Nature Photonics, vol. 8,

pp. 462-467, Jun 11 2014.

[4] M. Rösch, G. Scalari, M. Beck, and J. Faist, "Octave-spanning semiconductor laser," Nature Photonics, 2015.

[5] J. Faist, G. Villares, G. Scalari, M. Rösch, C. Bonzon, A. Hugi, and M. Beck, " Quantum cascade laser combs", Nanophotonics

(in print) (2016).

Contact: Dr. Guido Fuchs, More Information: uni-kassel.de/go/physikalisches_kolloquium