Open AccessDetermining the linewidth enhancement factor via optical feedback in quantum dot micropillar lasers
Author(s) -
Steffen Holzinger,
Sören Kreinberg,
Brett H. Hokr,
Christian Schneider,
Sven Höfling,
Weng W. Chow,
Xavier Porté,
Stephan Reitzenstein
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.031363
Subject(s) - laser linewidth , semiconductor laser theory , laser , quantum dot laser , optics , quantum dot , optoelectronics , spontaneous emission , materials science , physics
The linewidth enhancement factor α is a key parameter determining the spectral and dynamical behavior of semiconductor lasers. Here, we propose and demonstrate a method for determining this parameter based on a direct measurement of variations in the laser gain and emission spectrum when subject to delayed optical feedback. We then use our approach to determine the pump current dependent linewidth enhancement factor of a high-β quantum dot micropillar laser. The validity of our approach is confirmed comparing it to two conventional methods, one based on the comparison of the linewidths above and below threshold and the other based on injection locking properties. Furthermore, the pump power dependence of α is quantitatively described by simulations based on a quantum-optical model.