Optical cryptography with C-point vector beams

Mansi Baliyan

doi:10.1016/j.optlaseng.2024.108337

2024-09-01

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Mansi Baliyan

Naveen K. Nishchal *

DOI：10.1016/j.optlaseng.2024.108337

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摘要

En 中文

Considering the concern of efficient data handling in information security applications, we propose a novel method for high-dimensional image encoding onto two spatially separated polarization components of C-point vector beams. These beams, known for their spatially varying polarization distribution are generated by the superposition of different magnitude of optical vortex modes modulated into orthogonal polarization basis. Our approach harnesses the unique characteristics of light carrying spatially concatenated orthogonal states of optical vortices for image encoding unlike traditional optical cryptosystems that rely on the spatial distribution of amplitude, phase, and polarization of light. Through the superposition of phase holograms corresponding to images encoded within both the polarization components, each exhibits distinct magnitudes of optical vortex modes at each pixel. The proposed approach allows for secure image encryption into C-point vector beams. The utilization of optical vortices associated with orbital angular momentum offers flexibility in terms of allowing for the selection of infinite integer values of topological charge. This versatility inspires us to encode image using an array of vortices, thereby ensuring stable encoding and minimize quality degradation in practical implementations. Furthermore, exploiting the two orthogonal polarization components of light enhances high-dimensional encoding, offering a solution to the 'capacity crunch' issue in secure optical communication systems. Manipulation within two degrees of freedom of light is demonstrated through a non-interferometric experimental set-up employing dual-pass modulation approach which simplifies vector beam generation.

Keyword:

Optical cryptography

Vector beam

C -point polarization singularity

Dual -pass modulation

Spatial light modulator