Lei de potência na distribuição de intensidade de padrão de Speckles interagindo com vapor de Césio

Abstract

The Speckles Pattern is a wave interference phenomenon that has been studied in many fields, including optics. This phenomenon occurs when a beam of coherent light strikes a rough/rough surface producing a reflected or transmitted beam with a random spatial variation of intensity (intensity distribution). The speckle statistic is a good tool to understand nonlinear phenomena in optics and the nonlinear laser-medium interaction, for example. Therefore, this dissertation focuses on the investigation of Speckles Patterns propagating through a cesium vapor. We report that the interaction between the intensity distribution-atomic medium can change the character of the speckle statistics and that the nonlinear effects are intrinsically responsible for the change in the intensity distribution. First, we analyzed the influence of the nonlinear refraction index (n2) on the propagation of Speckles Patterns in the atomic medium, verifying that in the self-defocus regime (n2 < 0), the Speckles pattern presents a "blurred"image and that there is a decrease in the probability of getting high intensities. While for self-focusing (n2 > 0) the Speckles pattern focuses on multiple luminous points and with a high probability of obtaining high intensities. In this regime is where we observe that the intensity distribution can follow a Power Law. Knowing that for n2 > 0 a Power Law is observed in the intensity distribution, we focused on investigating which parameters corroborate its emergence. Finally, when examining the effects of light-atomic medium interaction on speckle statistics, it was found that n2,(e f f) ∗ I (the product of the effective nonlinear refractive index and the intensity) modifies in the Probability Density Function of intensity, resulting in a Power Law distribution.