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Proceedings Paper

Frequency comb operation of long-cavity terahertz quantum-cascade lasers
Author(s): M. Wienold; B. Röben; L. Schrottke; H. T. Grahn
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Paper Abstract

We investigated the multi-mode operation of long-cavity terahertz quantum-cascade lasers (l ≥ 7.5 mm). For QCLs based on an active region design with longitudinal optical (LO) phonon transitions, emission with 30–40 strong modes in a range of more than 270 GHz (9 cm-1) is observed. For certain operating conditions, we found evidence for stable frequency comb operation, which has been further proven by a self-mixing technique. In general, the multimode dynamics is characterized by a complex alternation of broad- and narrow-beat note regimes for these devices. In contrast, only a single narrow-beat note regime was observed for a different long-cavity device based on a bound-to-continuum active region, for which the emission comb spans only 33 GHz (1.1 cm-1). We further report a technique based on a tunable bandpass filter to confirm the presence of weak emission modes in the periphery of THz combs, which allowed for the unambiguous detection of modes within a dynamic range of 35 dB. We found that the 35-dB width of the comb can exceed the 20-dB width by a factor of two.

Paper Details

Date Published: 10 March 2016
PDF: 9 pages
Proc. SPIE 9767, Novel In-Plane Semiconductor Lasers XV, 97671A (10 March 2016); doi: 10.1117/12.2208128
Show Author Affiliations
M. Wienold, Paul-Drude-Institut für Festkörperelektronik (Germany)
Humboldt-Univ. zu Berlin (Germany)
Deutsches Zentrum für Luft- und Raumfahrt e.V. (Germany)
B. Röben, Paul-Drude-Institut für Festkörperelektronik (Germany)
L. Schrottke, Paul-Drude-Institut für Festkörperelektronik (Germany)
H. T. Grahn, Paul-Drude-Institut für Festkörperelektronik (Germany)

Published in SPIE Proceedings Vol. 9767:
Novel In-Plane Semiconductor Lasers XV
Alexey A. Belyanin; Peter M. Smowton, Editor(s)

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