Generation of tuneable 589nm radiation as a Na guide star source using an optical parametric amplifier

We describe a 5.5W 589nm source based on a passively mode-locked Nd:YVO4 laser and a multi-stage Lithium Triborate optical parametric amplifier seeded by a tuneable semiconductor laser. We show this system can produce rapidly tuneable, transform-limited pulses in near diffraction-limited beams at 589nm, useful for Na guide star applications. The attraction of this scheme is that it can be assembled from commercially available hardware and is readily scalable to high average powers.