Exploration of Type-I Intermittency Leading to Chaos in a Passively Q-Switched Tm:YLF Laser Emitting at 2.3 μm

Q-switched Tm lasers operating at 2.3 μm are of great interest in view of their potential applications [1], [2]. However, these lasers seem to exhibit systematic instabilities and chaotic behaviors [3]. Despite extensive research, the mechanisms driving these instabilities remain not analyzed. This study tends to investigate the chaotic dynamics in a Tm:YLF laser operating at 2.3 μm, highlighting an atypical type-I intermittency route to chaos. This chaotic behavior with intermittency appears inherently linked to the cascade transitions within the laser [4]. Using a Cr:ZnSe saturable absorber, the laser transitions from stable to chaotic regimes changing the pump power. Analytical methods, including Poincaré maps, phase space reconstruction and entropy calculations, reveal laminar phases and cubic behaviors consistent with type-I intermittency scenario (Fig. 1.c). Moreover, entropy rises from 0 (stable) to 1.55 (chaotic) versus pump power, giving a quantitative criterion to discriminate the different laser behavior. Moreover, phase-space reconstructions (Fig. 1.d) confirm the chaotic nature of the system giving an embedding dimension of 10 (Fig. 1.e).