Theory of spatial mode competition in a fiber amplifier
Abstract
Theory of monochromatic wave field amplification in a waveguide array based on expansion of the wave field in terms of guided array modes is developed. Equations for the expansion coefficients include cross-modal gain, which completely changes behavior of the amplified wave field. Analysis of two-mode amplification reveals new unusual features in characteristics of two-mode amplifier. Instead of unlimited growth of both modes for incoherent fields, one of the modes grows with no limit and suppresses the lower-power mode. Effects associated with the cross-modal gain are illustrated analytically on a system of two thin parallel planar waveguides. Conditions are found when a mode with lower gain can become the dominant one at the output of amplifier.
Keywords
Cite
@article{arxiv.0705.1261,
title = {Theory of spatial mode competition in a fiber amplifier},
author = {Anatoly P. Napartovich and Dmitry V. Vysotsky},
journal= {arXiv preprint arXiv:0705.1261},
year = {2009}
}
Comments
Corrected version, model in section II has been made more optical. Paper is submitted to Phys. Rev. A