Generating scalar and vector modes of Bessel beams utilizing holographic axicon phase with spatial light modulator

Abstract

This paper presents an efficient method for the generation of scalar as well as vector modes of Bessel–Gaussian (BG) beams by utilizing a computer generated phase-only mask encoded using the spatial light modulator (SLM). A phase-only hologram corresponding to the transmission function of axicon combined with a spatial phase plate (SPP) is used. The SPP converts a Gaussian field into a phase singular beam of order l associated with an azimuthally varying spiral wavefront structure and the axicon helps achieve non-diffracting BG beams. A compact experimental setup is proposed for the experimental realization of BG fields possessing both homogeneous as well as spatially varying polarization distributions across the transverse plane. Scalar BG beams are generated through the modulation of the combined phase patterns of axicon and SPP with the SLM. Vector BG beams are generated in two special cases: azimuthally and radially polarized inhomogeneous distributions through dual-passes from the SLM. A non-interferometric technique of dual-pass modulation, from the phase patterns displayed on a single SLM, which is divided into two halves, has been utilized. Here, scalar BG beams with orthogonal phase structure are encoded into orthogonal components of incoming light for vector BG beam generation.