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Proceedings Paper

Quantum dot cascade heterostructure based on in-plane dipole moments for unipolar infrared cascade lasers
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Paper Abstract

Quantum cascade lasers based on planar quantum wells have emerged as a leading candidate for infrared laser sources. However, these lasers are ultimately limited by phonon emission, and exhibit useful optical gain only for the tranverse magnetic polarization. Quantum dot (QD) gain material to replace the planar gain regions is very attractive because the unipolar approach can then lead to both a phonon bottleneck, and surface emission. However, tunneling phenomenon is quite different for unipolar QD injection, and designs that follow the now standard approaches based on planar quantum wells are known to have unfavorable tunneling characteristics. In this paper we present a new device design based on QDs that can lead to important advantages for realizing high performance unipolar injection infrared lasers. The new quantum dot cascade laser design is based on controlling electron tunneling in the different quantum dimensional systems, from zero-dimensional to two-dimensional, to both block as well as enhance tunneling in a gain stage so as to obtain the population inversion necessary for infrared gain. This new device, the quantum dot cascade laser (QDCL), can operate with a phonon bottleneck, and therefore can exhibit improved high temperature performance in contrast to planar heterostructure unipolar devices. In addition, the zero-dimensional confinement can also provide transverse electric polarization in the radiation field, and therefore surface emission. Epitaxial growth experiments based on self-organized quantum dots to realize the new QDCL approach are presented and discussed.

Paper Details

Date Published: 1 June 2005
PDF: 7 pages
Proc. SPIE 5792, Laser Source and System Technology for Defense and Security, (1 June 2005); doi: 10.1117/12.609709
Show Author Affiliations
Mathilde Gobet, The Univ. of Texas at Austin (United States)
Dennis G. Deppe, The Univ. of Texas at Austin (United States)

Published in SPIE Proceedings Vol. 5792:
Laser Source and System Technology for Defense and Security
Gary L. Wood, Editor(s)

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