Experimental study on laser pattern formation by strong nonlinear effects in rubidium atomic hot vapor

Abstract

There are abundant nonlinear effects in atomic vapor. In this paper, the phenomenon of laser breaking up into filaments is studied in the near-resonant rubidium atomic vapor，which is induced by the strong nonlinear Kerr effect. When the continuous-wave laser beam with transverse Gaussian distribution passes through the atomic vapor, the pattern arising from the coherent superposition of the diffraction patterns of filaments is observed. We also investigated the influence on the mode pattern by input power of laser, the temperature of the vapor cell and the frequency detuning of pump light. Due to the hyperfine structure of rubidium atoms, the four-wave mixing effect exists in hot rubidium atomic vapor, which is related to the third-order nonlinear effect closely. The Raman gain of the Stokes and anti-Stokes photons is observed by scanning the frequency of the probe beam.