Spontaneous chaos and extreme events in a solid-state laser with the transverse-mode-degenerate cavity configuration.

In this Letter, we theoretically analyze cavity beam propagation in a gain medium and cavity using the rate equation and generalized Huygens integral, respectively. Spontaneous chaos and extreme events (EEs) occurred around the transverse-mode-degenerate cavity configuration because of transverse-mode competition. A closed occurrence region relating to varying pump power and cavity length was observed. The experimental results in a continuous-wave Nd:YVO4 laser agreed with the aforementioned numerical results. Because gain effect is essential to a laser, we assume that EEs can be intrinsic and universal in a well-aligned laser system if it satisfies the specific transverse-mode competition.

Selection rule for cavity configurations to generate cylindrical vector beams with low beam quality factor.

Considering the birefringence of the gain medium, we propose a selection rule for designing cavity configurations that enable the generation of radially and azimuthally polarized laser beams with a low beam quality factor, i.e., high beam quality. Using this rule, all stable regions can support cylindrical vector (CV) beams by using the position of the end mirror as the tuning parameter to vary the cavity configuration. Such cavity configurations tend to sustain the fundamental or lowest-order CV beam, and radially or azimuthally polarized beams can be obtained simply by varying the tuning parameter. Based on experimental measurements of the beam quality factor and polarization characteristics, we verified our analyses and simulations for a four-element laser system.

Chaos and extreme events in an azimuthally polarized Nd:GdVO4 laser with pump modulation.

Nonlinear dynamics and extreme events were explored in a spatially distributed polarization laser based on an azimuthally polarized Nd:GdVO4 laser with pump modulation. When the modulation frequency approached the relaxation oscillation frequency, a period-doubling route to chaos was observed with an increasing modulation depth, and spatiotemporal extreme events occurred with the generation of the chaos. An efficient azimuthal polarization was kept, even though the intensity fluctuated in the chaotic region.

Periodic and chaotic dynamics in a passively Q-switched Nd:GdVO4 laser with azimuthal polarization.

A period-doubling route to chaos was observed in a passively Q-switched Nd:GdVO4 laser beam with azimuthal polarization. At a period of two, the peak intensities gradually varied with the azimuthal angle. When the pump power was increased, the chaotic behavior was spatiotemporal, but the polarization was still azimuthal. To the best of our knowledge, this is the first report of spatiotemporal chaos under a stationary spatial distribution of the polarization.