High-power Er:YAG laser with quasi-top-hat output beam

A simple method for simultaneously exciting the fundamental (TEM00) transverse mode and first order Laguerre-Gaussian (LG(01)) donut mode in an end-pumped solid-state laser to yield a quasi-top-hat output beam is reported. This approach has been applied to an Er:YAG laser, in-band pumped by an Er, Yb fiber laser, yielding 9.6 W of continuous-wave output at 1645 nm in a top-hat-like beam with beam propagation factor (M-2) < 2.1 for 24 W of incident pump power at 1532 nm. The corresponding slope efficiency with respect to incident pump power was 49%. The prospects of further scaling of output power and improved overall efficiency are considered. (C) 2012 Optical Society of AmericaThis work was supported by the Engineering and Physical Sciences Research Council (EPSRC) and by the Electro-Magnetic Remote Sensing Defence Technology Centre, established by the UK Ministry of Defence