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Proceedings Paper

Low-threshold superlattice quantum cascade laser emitting at λ = 103 μm and operating up to 70 K in continuous wave
Author(s): Jesse Alton; Stefano Barbieri; Harvey E. Beere; John Fowler; Edmund H. Linfield; David A. Ritchie
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Paper Abstract

We demonstrate the operation of a superlattice GaAs/AlGaAs quantum cascade laser emitting at λ = 103 μm. The maximum operating temperature is 95K in pulsed mode and 70K in continuous wave. At 4K, we measured a peak output power in the tens of mW range and a threshold current density of 110 A/cm2 (300 A/cm2 at 90K). We attribute this excellent performance to a low ratio between the lower and upper state lifetimes, as well as to a low leakage current. These characteristics are highlighted by a pronounced decrease of the differential resistance at threshold and by the fact that the slope efficiency remains constant up to approximately 70K. At any temperature, we observe an abrupt decrease of the output power at the breaking of miniband alignment, corresponding to a strong negative differential resistance feature in the current/voltage characteristics. Ultimately, this effect limits the operation of the device at high temperatures. By comparing this laser with a previous design, we will outline the importance of (i) having a diagonal rather than vertical laser transition in real space, and (ii) avoiding possible intersubband re-absorption of the emitted radiation.

Paper Details

Date Published: 8 April 2004
PDF: 10 pages
Proc. SPIE 5354, Terahertz and Gigahertz Electronics and Photonics III, (8 April 2004); doi: 10.1117/12.537784
Show Author Affiliations
Jesse Alton, Univ. of Cambridge (United Kingdom)
Stefano Barbieri, TeraView Ltd. (United Kingdom)
Harvey E. Beere, Univ. of Cambridge (United Kingdom)
John Fowler, Univ. of Cambridge (United Kingdom)
Edmund H. Linfield, Univ. of Cambridge (United Kingdom)
David A. Ritchie, Univ. of Cambridge (United Kingdom)

Published in SPIE Proceedings Vol. 5354:
Terahertz and Gigahertz Electronics and Photonics III
R. Jennifer Hwu, Editor(s)

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