Beam shaping with segmented devices

Abstract

The ability to tailor light in all its degrees of freedom has led to various applications in fields such as medical technology, industrial, military and free-space communi- cation. While a surfeit of techniques exists to shape light such as the spatial light modulator (SLM), diffractive optical elements (DOEs), and deformable mirrors to name a few, high-power beam shaping is still a challenge. DOEs and the deformable mirrors are beneficial due to their ability to shape high power beams, however, they are costly and complex to fabricate. We use a liquid crystal on silicon spatial light modulator (LCoS-SLM) to investigate the minimal amount of steps or segments re- quired to shape a phase of interest with high fidelity. In Chapter 3 we illustrate that we only require 10 multi-level steps to generate high fidelity phase structures for or- bital angular momentum phase (vortex beam), cubic phase (Airy beam) and axicon phase (Bessel beam in the near-field and annular ring in the far-field) as examples. In Chapter 4 we show a relationship between the segmented modulator geometry and the transverse phase structure. Various phase structures with phase configurations were demonstrated, the segments geometry that matches the geometry of the phase structure requires less segments to align with the phase discontinuities. We also demonstrate how rotating the phase of a non-symmetric phase structure may affect the fidelity of a beam profile. This work will serve as a guide to those who wish to simulate first with the LCoS-SLM before the physically fabricate the aforementioned devices for beam shaping.