Chaotic dynamics in passively Q-switched Tm:LiYF4 laser operating at 2.3 μm on the 3H4 → 3H5 transition

Abstract

We report on the chaotic dynamics in a passively Q-switched 2.3-μm thulium laser operating on the 3H4 → 3H5 transition. The experiment exploits a Tm:LiYF4 crystal and various laser cavity configurations, involving an optional cascade laser on the 3F4 → 3H6 transition at 1.9 μm. The saturable absorber employed is Cr2+:ZnSe, which is exclusively saturated by the 2.3 μm laser. An analysis of the Q-switched dynamics shows a pronounced inclination of the laser operation toward the unstable and chaotic behavior. To understand the origins of this chaos, we monitor the population of the metastable 3F4 level via cascade laser operation at 1.9 μm, underlying this variable as an interesting parameter to survey chaotic instabilities.