Analysis of self-focusing beams of concentric symmetry in As2S3 glass using a near-field scanning optical microscope

Abstract

The self-focusing (SF) effect for concentric laser beams passing through As2S3 glass was studied using a near-field scanning optical microscope. In the case of radially symmetric laser beams at the wavelength 633 nm, there was no special bright spot caused by the SF effect at local areas, except for the central part of the light beam. The minimum beam size that was arrested by nonparaxiality was less than 0.3 μm, which is approximately equal to the wavelength of light in the As2S3 glass, 0.265 μm. Qualitatively, the experimental results agreed with the theoretical prediction of the nonparaxial approximation.