Title :
Beam quality factor of higher order modes in a step-index fiber
Author :
Yoda, Hidehiko ; Polynkin, Pavel ; Mansuripur, Masud
Author_Institution :
Fac. of Eng., Utsunomiya Univ.
fDate :
3/1/2006 12:00:00 AM
Abstract :
The beam quality factor (or M2-parameter) for linearly polarized (LP)-modes of a step-index fiber is calculated in a closed form, as a function of the fiber V-number. It is shown that M2 sharply peaks for all fiber modes when they are close to cutoff. Particularly simple expressions are derived in the limit Vrarrinfin. Two practically important coherent superpositions of modes are considered for which the degree of degradation of the beam quality due to the higher order mode content is calculated. The reported results can be useful for designing large-core high-power fiber lasers, amplifiers, and fiber-based beam delivery systems, when preservation of the spatial beam quality is important
Keywords :
Q-factor; laser beams; optical fibre amplifiers; optical fibre polarisation; beam quality factor; coherent mode superpositions; fiber V-number; fiber amplifiers; fiber-based beam delivery systems; high order modes; high-power fiber lasers; large-core fiber lasers; linearly-polarized modes; spatial beam quality; step-index fiber; Degradation; Fiber lasers; High power fiber lasers; Laser beams; Laser modes; Optical beams; Optical design; Optical fiber polarization; Optical fibers; Q factor; Beam quality factor; fiber modes; multimode fiber;
Journal_Title :
Lightwave Technology, Journal of
DOI :
10.1109/JLT.2005.863337
