Estudo experimental da refração não linear em vapor de césio utilizando a técnica z-scan

Abstract

The z-scan technique consists in measurement of the variation of the radial intensity of a Gaussian laser beam induced by self-focusing or self-defocusing while propagating through a nonlinear medium. These variations are deduced through detection of the beam transmitted through a small, fixed aperture. After the seminal work by Sheik-Bahae et al. [30] in 1990, a lot of work has been done studying the nonlinearity of solids. By comparison, very little has been done with resonant atomic vapors, but rich results were obtained due to the very high atomic susceptibilities at resonance [33, 42]. In this work we report our measurements using a focused laser beam sent through a thermal cesium vapor. We have carried out many runs of z-scan for different frequencies of the laser tuned in the wings of the cesium Doppler-broadened D2 transition (6S1/2-6P3/2 at 852 nm) and observed the changes in the radiation transmitted through a fixed aperture.