Laser shaping and optical power limiting of pulsed Laguerre-Gaussian laser beams of high-order radial modes in fullerene C ₆₀

We study the strong nonlinear optical dynamics of nanosecond pulsed Laguerre–Gaussian laser beams of high-order radial modes with zero orbital angular momentum propagating in the fullerene C ₆₀ molecular medium. It is found that the spatiotemporal profile of the incident pulsed Laguerre–Gaussian laser beam is strongly reshaped during its propagation in the C ₆₀ molecular medium. The centrosymmetric temporal profile of the incident pulse gradually evolves into a non-centrosymmetric meniscus shape, and the on-axis pulse duration is clearly depressed. Furthermore, the field intensity is distinctly attenuated due to the field-intensity-dependent reverse saturable absorption, and clear optical power limiting behavior is observed for different orders of the input pulsed Laguerre–Gaussian laser beams before the takeover of the saturation effect; the lower the order of the Laguerre–Gaussian beam, the lower the energy transmittance.