Three-dimensional finite-difference time-domain analysis of gas ionization

The propagation of intense optical beams in a gas undergoing ionization is analyzed through a three-dimensional finite-difference time-domain (3D-FDTD) scheme. The propagation dynamics include the effects of diffraction, nonlinear self-focusing, and ionization. For sufficiently intense optical beams the neutral gas undergoes ionization, generating a plasma which tends to defocus the beam. Balancing of diffraction, plasma defocusing, and nonlinear self-focusing may lead to self-guided results. In this paper, necessary relations have been introduced into the conventional FDTD formulation to account for the nonlinear behaviors. Furthermore, a concurrent utilization of computer memory and disk storage helps us in expanding the simulation domain to a considerable extent. Results of various simulation scenarios are offered using our FDTD code. Simulations indicate that gas ionization has considerable effects on the propagation characteristics of intense optical beams.