Solid-state diode pumped laser employing oscillator-amplifier

A solid-state laser system includes a solid state oscillator for generating a laser beam and a multiple stage amplifier for increasing an energy of the beam. The oscillator includes an elongated housing having an elongated cavity defined therein, a solid state rod disposed within the cavity, a pumping source for exciting laser active species within the rod, and a resonator including the rod disposed therein for generating a laser beam. The multiple-stage amplifier preferably includes an even number of stages. One or more pairs of compensating stages may be mutually rotated about the beam axis by substantially 90°, with each pumping direction parallel to the polarization direction of the beam. A first stage may be side-pumped by a pumping radiation source in a direction substantially parallel to a polarization direction of the beam generated by the oscillator resonator. A divergence adjusting optic may be disposed before at least one stage of the amplifier for adjusting a divergence of the beam prior to entering the amplifier stage. A divergence adjusting optic may be disposed after the amplifier stage having the divergence adjusting optic before it and before a second amplifier stage, and may be adjustable as to its divergence adjustment.