Experimental study of nonlinear focusing in a magneto-optical trap using a Z-scan technique

Abstract

We present an experimental study of $Z$-scan measurements of the nonlinear response of cold Cs atoms in a magneto-optical trap. Numerical simulations of the $Z$-scan signal accounting for the nonuniform atomic density agree with experimental results at large probe beam detunings. At small probe detunings a spatially varying radiation force modifies the $Z$-scan signal. We also show that the measured scan is sensitive to the atomic polarization distribution.