Design of Scalable Optical Decoder based on Hexagonal Plasmonic Modes induced on Topological Insulator Surface States.

In the present work, optical decoder based on hexagonal plasmonic lens encrypted on topological insulator is designed. Using Finite Difference Time Domain (FDTD) simulation we have shown 2D optical lattice of scalar vortices in hexagonal plasmonic lens using surface states of topological insulator (Bi1.5Sb0.5Te1.8Se1.2). To ensure feasible and flexible physical dimensions, scaling of the optical device is proposed via increasing area density of vortices. This is numerically obtained by changing radius of hexagonal lens or decreasing incident wavelength. Using these scalable optical vortex lattices, a device scheme is proposed for storing or decoding information. Advantage of scaling in optical devices without any additional processing step shows the promise of this technology for future devices. Simulation results are further validated by detailed theoretical calculation of electric field intensity and phase distribution.