Emission enhancement of femtosecond laser-induced breakdown spectroscopy using vortex beam

Abstract

This paper used femtosecond Gaussian and vortex beams to ablate a Cu target and generate Cu plasmas. A Gaussian beam pulse is shaped into a vortex beam by a vortex wave plate (topological charge m = 1). The spectral intensity of Cu plasmas produced by the two lasers was measured, finding that the spectra with vortex beam were stronger than that with Gaussian beam. The spectral intensity was doubled by simply changing the Gaussian beam into the vortex beam. In addition, the position for maximum Cu atomic line emission along with the laser path was closer to the position of focusing-lens with increasing laser energy. Finally, the Boltzmann plot calculated the plasma temperature, finding that the plasma temperature with the vortex beam was also higher than that with the Gaussian beam. The results indicated that vortex beams could improve the spectral intensity of the femtosecond laser-induced plasmas.