Ultrafast thermalization dynamics in silicon wafer excited by femtosecond laser double-pulse vortex beam

The ultrafast thermalization dynamics of silicon wafers excited by a femtosecond laser double-pulse vortex beam was theoretically investigated via multi-physical fields simulations. A self-consistent model was developed, which comprehensively considers for the transient properties of optical, electronic and thermal parameters to predict the vortical thermalizations in silicon wafers. The spatial-temporal evolutions for carrier density and vortical temperature fields in nonequilibrium state of photo-excited silicon wafer are obtained in details. It is revealed that the photo-generated carrier can be significantly multiplied by utilizing a femtosecond laser doublepulse vortex beam, simultaneously amplifying the vortical thermalization dynamics of silicon wafer. The results can be attributed to two factors of the enhanced light absorption and the amplified carrier-phonon coupling dynamics via double-pulse vortex beam excitations. The results can provide for basic insights into the vortical heating dynamics of femtosecond laser double-pulse vortex beam interactions with semiconductors, putting forward the feasibility of advanced vortex beam applications for STED imaging, ultrafast SERS sensing and laser fabrication of sophisticated structures, etc.