Theoretical study on saturable absorption using Gaussian vortex beam z-scan

Abstract

The study of nonlinear absorption has potential applications as saturable absorption and optical limiting character in scientific and engineering technology. In this work, we report on the Gaussian vortex beam z-scan to study the saturable absorption in the two-level model. For a given material and laser beam parameters, even though vortex beam shows less saturable absorption nature than the conventional Gaussian beam but not much appreciated. The open aperture z-scan peak is narrower for Gaussian vortex beam as compared with Gaussian beam. Also, in the presence of pico- and femto-second laser pulses, the central dark core of Gaussian vortex beam can provide a stable and accurate z-scan profile with avoiding thermal and other nonlinear optical effects at the beam waist of z-scan in the saturable absorber characterization. With including above mentioned points, we have shown how the Gaussian vortex z-scan is superior to the conventional Gaussian beam z-scan for saturable absorber characterization. Though discussed for single-photon absorption, it may extend to multi-photon absorption.