Towards polarization steganography

TL;DR

This paper introduces a novel polarization-based steganographic method using vector beams with spatially structured polarization states, enabling secure information hiding and retrieval through polarization analysis and spatial filtering.

Contribution

The work presents a new polarization steganography scheme utilizing partially polarized vector beams with spatially mapped polarization states for secure information hiding.

Findings

Successfully demonstrated polarization-based information hiding.

Achieved selective retrieval of hidden patterns using spatial filtering.

Validated the method with various parametric shapes.

Abstract

We propose and experimentally demonstrate a polarization--based steganographic scheme using partially polarized vector beams. In our approach, the spatially dependent polarization structure of the optical field serves as the carrier through which the hidden information can be retrieved. By engineering a vector beam whose polarization states populate a prescribed region of the Poincar\'e sphere, specifically, the equatorial disk, we establish a nontrivial mapping between transverse spatial coordinates and polarization states. Information retrieval is achieved by applying a spatial mask derived from a parametric curve defined within this region of the Poincar\'e sphere, followed by spatially resolved polarization analysis. We demonstrate the selective reconstruction of various parametric shapes, including polygonal and smooth curves, confirming that the hidden patterns are retrieved through the combined use of spatial filtering and polarization--domain mapping. Our results establish partially polarized vector beams as a flexible and experimentally accessible platform for polarization--based information hiding.