Design, fabrication and characterization of Computer Generated Holograms for anti-counterfeiting applications using OAM beams as light decoders

TL;DR

This paper introduces the design, fabrication, and testing of computer-generated holograms that encode information in light beams with orbital angular momentum, offering promising high-security anti-counterfeiting solutions.

Contribution

It is the first comprehensive work to design, fabricate, and characterize holograms encoding information in OAM-carrying light beams for anti-counterfeiting.

Findings

Successfully fabricated phase-only holograms using electron-beam lithography.

Demonstrated the holograms' ability to encode and decode OAM-based information.

Proved potential of these holograms as high-security anti-counterfeiting elements.

Abstract

In this paper, we present the design, fabrication and optical characterization of computer-generated holograms (CGH) encoding information for light beams carrying orbital angular momentum (OAM). Through the use of a numerical code, based on an iterative Fourier transform algorithm, a phase-only diffractive optical element (PH-DOE) specifically designed for OAM illumination has been computed, fabricated and tested. In order to shape the incident beam into a helicoidal phase profile and generate light carrying phase singularities, a method based on transmission through high-order spiral phase plates (SPPs) has been used. The phase pattern of the designed holographic DOEs has been fabricated using high-resolution Electron-Beam Lithography (EBL) over glass substrates coated with a positive photoresist layer (polymethylmethacrylate). To the best of our knowledge, the present study is the first attempt, in a comprehensive work, to design, fabricate and characterize computer-generated holograms encoding information for structured light carrying OAM and phase singularities. These optical devices appear promising as high-security optical elements for anti-counterfeiting applications.