Silvânia A. Carvalho

The asymmetric Goos–Hänchen effect

We show under which conditions optical Gaussian beams, propagating throughout an homogeneous dielectric right angle prism, present an asymmetric Goos–Hanchen (GH) effect. This asymmetric behavior is seen for incidence at critical angles and happens in the propagation direction of the outgoing beam. The asymmetric GH effect can also be seen as an amplification of the standard GH shift. Due to the fact that it only depends on the ratio between the wavelength and the minimal waist size of the incoming Gaussian beam, it can also be used to determine one of these parameters. Multiple-peak interference is an additional phenomenon seen in the presence of such asymmetric effects.

The use of the stationary phase method as a mathematical tool to determine the path of optical beams

We use the stationary phase method to determine the paths of optical beams that propagate through a dielectric block. In the presence of partial internal reflection, we recover the geometrical result obtained by using Snells law. For total internal reflection, the stationary phase method overreaches Snells law, predicting the Goos-Hanchen shift.

The frequency crossover for the Goos–Hänchen shift

For total reflection, the Goos–Hänchen (GH) shift is proportional to the wavelength of the laser beam. At critical angles, such a shift is instead proportional to the square root of the product of the beam waist and wavelength. By using the stationary phase method (SPM) and, when necessary, numerical calculations, we present a detailed analysis of the frequency crossover for the GH shift. The study, done in different incidence regions, sheds new light on the validity of the analytic formulas found in literature.

Experimental confirmation of the transversal symmetry breaking in laser profiles

The Snell phase effects on the propagation of optical beams through dielectric blocks have been matter of recent theoretical studies. The effects of this phase on the laser profiles have been tested in our experiment. The data show an excellent agreement with the theoretical predictions confirming the axial spreading modification and the transversal symmetry breaking. The possibility to set, by rotating the dielectric blocks, different configurations allows to recover the transversal symmetry. Based on this experimental evidence, dielectric blocks can be used as alternative optical tools to control the beam profile.