Modelling of the energy density deposition profiles of ultrashort laser pulses focused in optical media

The propagation of ultrashort laser pulses in dense optical media is investigated theoretically by solving numerically the nonlinear Schrödinger equation. It is shown that the maximum energy density deposition as a function of the pulse energy presents a well-defined threshold that increases with the pulse duration. As a consequence of plasma defocusing, the maximum energy density deposition is generally smaller and the size of the energy deposition zone is generally larger for shorter pulses. Nevertheless, significant values of the energy density deposition can be obtained near threshold, i.e., at lower energy than for longer pulses.