High-power laser operation of the first-order Laguerre-Gaussian (LG01) mode in a diode-laser-pumped Nd:YAG laser

High-power operation of an Nd:YAG laser with a first-order Laguerre-Gaussian (LG01) mode output by using a simple pump-beam-shaping technique in an end-pumped solid-state laser configuration is reported. An analytical expression for threshold pump power for determining the ring-shape pump beam dimension to allow direct excitation of the first-order LG01 mode is derived. This approach has been applied to a diode-laser-pumped Nd:YAG laser, yielding a 10.4 W LG01 mode output at 1064 nm in a beam with M2 ≈ 2.15 for a 21.7 W incident pump power. The experimental results for the threshold pump power and the beam quality under three different pump beam conditions are in very good agreement with the calculated values. The prospects for power scaling and improved laser performance will be discussed.