Colorful Optical Vortices with White Light Illumination

TL;DR

This paper demonstrates generating and decoding colorful optical vortices using incoherent white light by miniaturizing spiral phase plates with structural color filters, enabling applications in secure communication and anti-counterfeiting.

Contribution

It introduces a novel method to produce and utilize colorful optical vortices with white light, extending OAM applications to ambient lighting conditions.

Findings

Achieved spatio-temporal coherence with incoherent white light.

Created a reciprocal optical lock and key system using colorful vortices.

Extended pairwise coupling to a one-to-many matching scheme.

Abstract

The orbital angular momentum (OAM) of light holds great promise for applications in optical communication, super-resolution imaging, and high-dimensional quantum computing. However, the spatio-temporal coherence of the light source has been essential for generating OAM beams, as incoherent ambient light would result in polychromatic and obscured OAM beams in the visible spectrum. Here, we extend the applications of OAM to ambient lighting conditions. By miniaturizing spiral phase plates and integrating them with structural color filters, we achieve spatio-temporal coherence using only an incoherent white light source. These optical elements act as building blocks that encode both color and OAM information in the form of colorful optical vortices. Thus, pairs of transparent substrates that contain matching positions of these vortices constitute a reciprocal optical lock and key system. Due to the multiple helical eigenstates of OAM, the pairwise coupling can be further extended to form a one-to-many matching and validation scheme. Generating and decoding colorful optical vortices with broadband white light could find potential applications in anti-counterfeiting, optical metrology, high-capacity optical encryption, and on-chip 3D photonic devices.