Laguerre-Gauss beam generation in IR and UV by subwavelength surface-relief gratings

TL;DR

This paper reports the development of liquid-crystal-free q-plates using nanofabrication techniques to generate high-quality Laguerre-Gauss beams in UV and IR wavelengths, enabling high-power laser applications.

Contribution

It introduces a novel fabrication method for q-plates that operate across UV and IR ranges without liquid crystals, expanding their usability.

Findings

Successful fabrication of q-plates using e-beam lithography and etching.

Generation of high-quality Laguerre-Gauss beams in UV and IR.

Compatibility with high-power laser sources.

Abstract

The angular momentum of light can be described by the states of spin angular momentum, associated with polarization, and orbital angular momentum, related to the helical structure of the wave front. Laguerre-Gaussian beams carry orbital angular momentum and their generation can be done by using an optical device known as q-plate. However, due to the usage of liquid crystals, these components may be restricted to operate in specific wavelengths and low power sources. Here we present the fabrication and characterization of q-plates made without liquid crystals, using processes of e-beam lithography, atomic layer depositions and dry etch techniques. We exploit the phenomenon of form birefringence to give rise to the spin-to-orbital angular momentum conversion. We demonstrate that these plates can generate beams with high quality for the UV and IR range, allowing them to interact with high power laser sources or inside laser cavities.