Optical anisotropy induced by torsion stresses in LiNbO3 crystals: appearance of an optical vortex

TL;DR

This study investigates how torsion stresses induce optical anisotropy in LiNbO3 crystals, revealing a vortex with topological charge one and unique birefringence patterns, advancing understanding of stress-induced optical phenomena.

Contribution

It demonstrates the formation of an optical vortex with topological charge one caused by torsion in LiNbO3 crystals, showing control over spin-orbital coupling via torque.

Findings

Torsion causes a conical birefringence distribution.

A zero birefringence point exists at the crystal center.

An optical vortex with topological charge one appears under torsion.

Abstract

We report the results of studies of torsion effect on the optical birefringence in LiNbO3 crystals. We have found that twisting of those crystals causes a birefringence distribution revealing non-trivial peculiarities. In particular, it has a special point at the center of cross section perpendicular to the torsion axis where zero birefringence value occurs. It has also been ascertained that the surface of the spatial birefringence distribution has a conical shape, with the cone axis coinciding with the torsion axis. We have revealed that an optical vortex, with the topological charge equal to unity, appears under the torsion of LiNbO3 crystals. It has been shown that, contrary to the q-plate, both the efficiency of spin-orbital coupling and the orbital momentum of the emergent light can be operated by the torque moment.