Optimum energy absorption of a short-pulse laser in a doped dielectric slab

Abstract

A model is used to calculate energy absorption efficiency when a short-pulse laser impinges on a dielectric slab doped with an impurity for which the electrons have a resonant line at the laser wavelength. The amount of the energy resonant absorption is due to the overlapping between laser spectrum and resonance spectrum. The energy absorption efficiency can be maximized for a certain degree of doping concentration (at a given pulselength) and also for a certain pulselength (at a given doping concentration). For a modest amount of impurity, the resonant absorption may increase the fraction of energy absorption up to tens of percent of laser energy at 100s optical cycles when the laser wavelength is tuned within 1% of the resonant line. Dimensionless parameters are constructed so that the scaling to various parameters: laser wavelength, laser pulselength, dielectric constant, slab thickness, impurity concentration, resonant linewidth, and separation between the laser wavelength and the line resonance, could easily be obtained.