Unconventional generation of optical vortex beam using axicon pair and a birefringent lens: Validation of plasmonic excitation

摘要

We generate a nondiffracted Bessel beam using an axicon. A simple setup is presented to generate a zero order Bessel beam. Moreover, we introduce certain modifications in this optical setup for unconventional generation of an optical vortex beam using an axicon pair and a birefringent lens. An optical vortex beam with a topological charge of 1 is generated, and the corresponding spiral pattern has been demonstrated, which confirms the presence of orbital angular momentum in the optical vortex beam. Further, plasmonic excitation is validated using both zero order and first order Bessel beams. Our approach to confirm the presence of surface plasmon resonance relies on the use of a Wollaston prism. We are able to separately identify the coupling of surface plasmons with the p-polarized components via the absence of the corresponding annular beam.