We demonstrate that appropriately designed doped multimode fibers provide robust single-mode output when used within a fiber laser cavity. Using a novel large-mode-area fiber, we demonstrate what we believe to be record single-mode (<i>M</i><sup>2</sup> <1.2) pulse energies of >0.5 mJ from a <i>Q</i> -switched fiber laser and even higher pulse energies (as high as 0.85 mJ) with slightly compromised spatial-mode quality (<i>M</i><sup>2</sup><2.0) . This approach offers significant scope for extending the range of single-mode output powers and energies that are achievable from fiber-laser–amplifier systems.
© 1998 America
(060.2280) Fiber optics and optical communications : Fiber design and fabrication
(060.2320) Fiber optics and optical communications : Fiber optics amplifiers and oscillators
(060.2410) Fiber optics and optical communications : Fibers, erbium
(140.3540) Lasers and laser optics : Lasers, Q-switched
H. L. Offerhaus, N. G. Broderick, D. J. Richardson, R. Sammut, J. Caplen, and L. Dong, "High-energy single-transverse-mode Q-switched fiber laser based on a multimode large-mode-area erbium-doped fiber," Opt. Lett. 23, 1683-1685 (1998)