Topological insulator Sb_2Te_3 as an optical media for the generation of ring-shaped beams

Abstract

Hexagonal nanosheets of Sb2Te3 single crystals with uniform morphology are successfully synthesized through a solvothermal method. We experimentally demonstrate that topological insulator Sb2Te3 as an optical media can be used for the generation of ring-shaped beams based on a giant optical nonlinearity and the effect of graded-index plasma lens. Good propagation properties in free space are exhibited by the generated ring-shaped beam and the dark spot size of ring-shaped beams can be conveniently controlled by adjusting the power of the pump beam. We also find that it is more easily to generate a ring-shaped beam in the high concentration Sb2Te3 dispersion solution and the divergence angle of the ring-shaped beam increases as the concentration of dispersion solution increase.