Multiparameter bifurcations and mixed-mode oscillations in Q-switched CO2 lasers

Area of Science:

• Laser physics
• Nonlinear dynamics
• Quantum optics

Background:

• Carbon dioxide (CO2) lasers are crucial in various industrial and scientific applications.
• Understanding mixed-mode oscillations (MMOs) is essential for controlling laser behavior and stability.
• Previous models have simplified the complex dynamics of lasers, necessitating a more comprehensive approach.

Purpose of the Study:

• To investigate the origin and characteristics of mixed-mode oscillations (MMOs) in a fully molecular laser model.
• To analyze the role of bifurcations and isolas in the dynamics of Q-switched CO2 monomode lasers.
• To compare the dual four-level model with other established CO2 laser models.

Main Methods:

• Utilizing a fully molecular laser model (dual four-level model) for CO2 monomode lasers with a slow saturable absorber.
• Analyzing bifurcation diagrams and phase space portraits to identify MMOs and related phenomena.
• Comparing the dual four-level model with the 3:2 model and a fast saturable absorber model.

Main Results:

• Identified inherent isolas of periodic MMOs in Q-switched CO2 monomode lasers, dependent on pump parameter and detuning.
• Observed similarities and qualitative differences in MMOs across different CO2 laser models.
• Found evidence of isolas of MMOs in CO2 lasers with modulated losses.
• Characterized the homoclinic tangency to unstable periodic orbits, relevant to Gavrilov-Shilnikov theory.

Conclusions:

• MMOs and their associated isolas are fundamental features of Q-switched CO2 monomode lasers.
• The dual four-level model provides a more comprehensive understanding of MMOs compared to simpler models.
• The observed similarities in coarse-grained bifurcation diagrams suggest that MMOs in these different models belong to similar dynamical classes.