Energetic Bessel-Gauss pulses from diode-pumped solid-state lasers

We discuss the generation of Bessel–Gauss pulses directly from a diode-pumped solid-state laser. The laser resonator has a plano–concave configuration with the concave end mirror replaced with a diffractive phase element. As the active material, Nd-doped yttrium lithium fluoride (YLF) and GdVO₄ crystals have been used. The pulsed operation is obtained by passively Q-switching the laser using Cr⁴⁺_:yttrium aluminum garnet (YAG) crystals with different unsaturated transmission coefficients. When guiding the pulses out from the resonator through the laser crystal, 5–10 ns long pulses with energies of  40-50 µJ and peak powers on the order of 10 kW are obtained. Even 70 µ J is possible, but this is achieved at the expense of slightly deteriorated beam quality in the far field.