title: Measurements of the alpha factor of a distributed-feedback quantum cascade laser by an optical feedback self-mixing technique.
abstract: We demonstrate measurements of the alpha factor of a distributed-feedback quantum cascade laser (QCL) by using a newly modified self-mixing interferometric technique exploring the laser itself as the detector. We find a strong dependence of the alpha factor on the injection current, ranging from -0.44 at 120 mA to 2.29 at 180 mA, which can be attributed to the inherent physics of QCLs.
authors.affiliation: Institute of Applied Phsyics, Darmstadt Univeristy of Technology, Schlossgartenstrasse 7, Darmstadt, Germany. jens.von.staden@physik.tu-darmstadt.de
authors.forename: Jens
authors.initials: J
authors.lastname: von Staden
authors.forename: Tobias
authors.initials: T
authors.lastname: Gensty
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Elsässer
authors.forename: Guido
authors.initials: G
authors.lastname: Giuliani
authors.forename: Christian
authors.initials: C
authors.lastname: Mann