40.1: Liquid Crystal Polymer Phase Plates Fabricated by Direct Laser Writing

Abstract

Optical vortex is a type of structured beam that carry orbital‐angular momentum (OAM) with different topological charge numbers. In this paper, we fabricate liquid crystal polymer phase plates to generate vortex beams by femtosecond 3D direct laser writing. Instead of using traditional photoresists, we compound liquid crystal monomers to create different structures. As a two‐photon direct laser writing technique, Nanoscribe is of high resolution of 100 nm, which implements high accuracy of our structures. We design spiral phase plate (SPP) with diameter of 25µm and a total height difference h of 1.25um to generate vortex beams with different topological charge numbers. We also set up the interference system to characterize the vortex beam. With the interference beam coupled, the presence of the vortex is experimentally indicated by the fringe “dislocation defects” at the center of the vortex in visible region. It presents a new way to fabricate liquid crystal polymer structures with unique birefringent properties, indicating new possibilities in photonics application.