title: Beam-quality factor of single-mode gain-guided fiber lasers.
abstract: The beam-quality factor M(2) for the fundamental LP01 mode of a step-index fiber is calculated in the presence of gain, in a closed form, as a function of the complex generalized V number. It is shown that the M(2) value of a single-mode gain-guided fiber laser can be arbitrarily large. The results are important for the interpretation of the beam-quality measurements in recent experiments on single-mode gain-guided fiber lasers.
authors.affiliation: Department of Electrical Engineering and Computer Science, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA.
authors.forename: Krishna Mohan
authors.initials: KM
authors.lastname: Gundu
authors.forename: Parisa Gandomkar
authors.initials: PG
authors.lastname: Yarandi
authors.forename: Arash
authors.initials: A
authors.lastname: Mafi