Dynamics instability in large-scale resonator based solid-state lasers

Similar with the mode instability in high-power fiber lasers induced by multimode interference and optical-thermal coupling, the output power and the beam quality of large-scale resonator based solid state lasers turn out to be irregularly temporal jitter along with high output power. This phenomenon is mainly due to medium intensity inhomogeneous which results from asymmetric laser oscillation within the unstable resonator and coupling between laser extraction and medium heat generation. For three different laser types, Nd: YAG thin-disk laser, Yb: YAG thin-disk laser and immersed liquid-cooled disk laser, theoretical analysis and numerical simulation are conducted in order to provide basic rules of laser output and distinct optical-thermal coupling mechanism. The results show that dynamics instability only appears within a certain interval since the dynamics presents saturation effects for the former two kinds of lasers. Thus, the instability can be avoided by choosing proper parameters. But for immersed liquid-cooled disk laser, it has obvious threshold under strong optical intensity, dynamics instability can be suppressed only by lower cooling absorption coefficient.