Optimization of plasmonic lens structure for maximum optical vortices induced on Weyl Semimetals Surface States

Optical vortices have a topologically charged phase singularity, as well as zero intensity distribution in the centre. Optical vortex creation is regarded as a significant source for information transmission for applications in quantum computing, encryption, optical communication, etc. In the present work, using Finite Difference Time Domain (FDTD) simulation we have calculated electric field intensity and phase distribution of 2D lattice of optical vortices generated from various polygonal plasmonic lens structures using surface states of Weyl semimetal (MoTe2). It has been shown that hexagonal lens is the best performing plasmonic lens. Further we have posited here a unified mathematical formulation for the optical electrical field and phase distribution in the near field for any polygonal plasmonic lens. Our theoretical calculation corroborates well with the FDTD results validating the proposed generalized formula. Such plasmonic lens structures demonstrating scaling behavior offer great potential for designing next generation optical memories.