Few-cycle strong light field dynamics in dielectric media

摘要

A nonlinear wave equation suitable for describing a propagation of a light pulse containing few oscillations of a strong electric field in isotropic dielectric media is deduced. It describes non-resonant dispersion of linear refractive index and non-inertial third-order non-linearity as well as inertia of dielectric non-linearity of electron nature, including parts caused by energy state population dynamics and free electron motion. The dependence of the conditions for the dominance of different physical factors in the self-action of few-cycle optical pulses in dielectrics on the intensity, duration, and spectrum of radiation has been theoretically analyzed. It is shown that the larger the pulse width and the central wavelength, the stronger the effect of plasma nonlinearity. For example, for a quartz glass in the field of pulses with a duration of 10 fs and a central wavelength of 780 nm, this nonlinearity mechanism is dominant at intensities exceeding 3(centre dot)10~(13) W/cm~(2).