Frequency doubled Nd:YVO/sub 4/ thin disk laser with 30% diode-to-green efficiency

Summary form only given. High power diode pumped solid-state lasers with second harmonic generation (SHG) offer compact, efficient and reliable visible light sources that may substitute less efficient gas lasers in medical applications and for the excitation of secondary laser sources. Most solid-state lasers however exhibit instabilities caused by optical nonlinear dynamics and the build up of the thermal lensing in the laser crystal when pumping power is changed rapidly. The well known thin disk laser geometry with longitudinal heat removal from the pumped laser crystal prevents strong thermal lensing. This property is used to achieve a stable mode and well defined SHG conversion conditions in the intracavity frequency doubled laser over the full power range. Due to the focal length of the thermal lens being much larger than the resonator length, the mode diameter both in the laser and the nonlinear (NLO) crystal is nearly independent of pumping power. Additionally, the nonlinear conversion efficiency is chosen to be smaller than that being required for maximum output power to reduce mode coupling.