Near-diffraction-limited operation of step-index large-mode-area fiber lasers via gain filtering.
We present, for the first time to our knowledge, an explicit experimental comparison of beam quality in conventional and confined-gain multimode fiber lasers. In the conventional fiber laser, beam quality degrades with increasing output power. In the confined-gain fiber laser, the beam quality is good and does not degrade with output power. Gain filtering of higher-order modes in 28microm diameter core fiber lasers is demonstrated with a beam quality of M(2)=1.3 at all pumping levels. Theoretical modeling is shown to agree well with experimentally observed trends.
Marciante
John R
JR
University of Rochester, Laboratory for Laser Energetics, 250 East River Road, Rochester, New York 14623-1299, USA. johnm@lle.rochester.edu
Roides
Richard G
RG
Shkunov
Vladimir V
VV
Rockwell
David A
DA