Spatio-temporal Evolution Dynamics of Ultrashort Laguerre-Gauss Vortices in a Dispersive and Nonlinear Medium

The additional degree of freedom as introduced by the orbital angular momentum (OAM) of light has revolutionized the various technological applications. Optical pulses with OAM have applications in the generation of twisted attosecond pulses, ultrafast spectroscopy, telecommunication, high harmonic generation and in many other areas of physics as well. In this paper, we present a numerical investigation of the propagation dynamics of ultrashort Laguerre Gauss (LG) vortices using nonlinear envelope equation (NEE) in a dispersive and nonlinear medium. Asymmetric splitting of ultrashort LG vortices in time at its bright caustic are observed above a certain pulse power. The asymmetric splitting owes its origin to spacetime focussing. We also observe that spatial evolution at pulse center (t=0 in pulse frame) and temporal evolution at bright caustic of the ultrashort LG vortex are quite similar. In the spectral domain, oscillatory structures are formed and above a certain peak power, we observe the generation of new frequency components with more intense lower frequency components.