The parasitic oscillations in a disk gain medium are refined by a rigorous electrodynamics study. The boundary conditions of an electromagnetic field decide not only the spatial distribution of the field (transverse eigenmodes) but also the spectrum of the field (longitudinal eigenmodes) due to the higher geometric symmetry of the disk. The novel dispersion relations only allow a few longitudinal eigenmodes. Because stable parasitic modes possess a larger spatial volume, in quasi-cw operating high-average-power solid-state lasers the longitudinal eigenmodes play a more important role than transverse ones in mode competition with the main laser. Furthermore, the polarizations are also selected by the boundary conditions, and a given eigenmode cannot possess radial polarization and azimuthal polarization components simultaneously.
© 2009 Optical Society of America
Lasers and Laser Optics
Original Manuscript: February 19, 2009
Revised Manuscript: May 28, 2009
Manuscript Accepted: June 17, 2009
Published: July 22, 2009
Xiao-Jun Wang and Xiao-Jian Shu, "Characteristics of parasitic eigenmodes in high-average-power disk lasers," J. Opt. Soc. Am. B 26, 1621-1626 (2009)