Polarisation structuring of broadband light.

Kevin J Mitchell,Sonja Franke-Arnold,Miles J Padgett,David B Phillips,Neal Radwell

doi:10.1364/oe.25.025079

Abstract

Spatial structuring of the intensity, phase and polarisation of light is useful in a wide variety of modern applications, from microscopy to optical communications. This shaping is most commonly achieved using liquid crystal spatial light modulators (LC-SLMs). However, the inherent chromatic dispersion of LC-SLMs when used as diffractive elements presents a challenge to the extension of such techniques from monochromatic to broadband light. In this work we demonstrate a method of generating broadband vector beams with dynamically tunable intensity, phase and polarisation over a bandwidth of 100 nm. We use our system to generate radially and azimuthally polarised vector vortex beams carrying orbital angular momentum, and beams whose polarisation states span the majority of the Poincaré sphere. We characterise these broadband vector beams using spatially and spectrally resolved Stokes measurements, and detail the technical and fundamental limitations of our technique, including beam generation fidelity and efficiency. The broadband vector beam shaper that we demonstrate here may find use in applications such as ultrafast beam shaping and white light microscopy.

Highlights

Over the last decade, advances in beam shaping technology have significantly improved our ability to manipulate and exploit the fundamental properties of light
Polarisation shaping requires independent spatial control of the intensity and phase of two orthogonal polarisation components. This is most commonly accomplished in a reconfigurable manner using liquid crystal spatial light modulators (LC-SLMs), which can spatially control the phase of incident light
We demonstrate the generation of broadband vector beams using our system

Summary

Introduction

Advances in beam shaping technology have significantly improved our ability to manipulate and exploit the fundamental properties of light. Modern beam shaping techniques allow us to arbitrarily structure the intensity and phase of a light beam [5, 6]; more sophisticated schemes can shape the local polarisation state of monochromatic light [7,8,9,10,11]. This ability to structure polarisation has recently gained interest as it provides an additional degree of control over a light beam, enabling the production of fields beyond the scope of those achievable with uniform polarisation. By independently shaping the intensity and phase of the two diffraction orders in stage 1, the intensity, phase and polarisation of the resultant monochromatic beam can be controlled

Objectives

Methods

Results

Conclusion