Lubomir M. Kovachev. Long range filament as a solitary wave
Natural Sciences / Physics / Optics
Submitted on: Jun 02, 2012, 10:35:32
Description: We investigate the propagation in air of laser pulses in linear and nonlinear regime. The mathematical model presented in the paper describes the propagation of pulses with narrow-band spectrum, as well as the evolution of broad-band ones. It is shown that the diffraction of pulses with super-broad spectrum or pulses with a few cycles under the envelope is closer to wave type. For such pulses, a new physical mechanism of balance between non-paraxial diffraction and third order nonlinearity appears. Exact analytical three-dimensional soliton solution in this regime is found. We investigate in more detail the nonlinear third order polarization, taking into account the carrier to envelope phase. This additional phase transforms the third harmonic term to GHz terms, which start to generate radiation when the pulse duration reaches the femtosecond range.