SELF-DEFOCUSING OF LIGHT IN COPPER-VAPOR

We report here the spatial distortion of a dye laser beam on propagati on through a column of copper vapour. With the dye laser frequency tun ed on the red side of the copper resonance line (578.2 nm), we have ob served self-defocusing of the beam. This was caused by the resonant no n-linearity associated with the electronic polarizability of the atomi c vapour. From our data on self-defocusing we have measured the nonlin ear refractive index n(2) for radiation red detuned with respect to th e copper atomic transition and found it to be in good agreement with o ur calculated value of n(2).