High-resolution grayscale image hidden in a laser beam

Fuyong Yue,Xiao-Fei Zang,Chunmei Zhang,Xianzhong Chen,Shuang Zhang,Dandan Wen,Brian D Gerardot

doi:10.1038/lsa.2017.129

Abstract

Images perceived by human eyes or recorded by cameras are usually optical patterns with spatially varying intensity or color profiles. In addition to the intensity and color, the information of an image can be encoded in a spatially varying distribution of phase or polarization state. Interestingly, such images might not be able to be directly viewed by human eyes or cameras because they may exhibit highly uniform intensity profiles. Here, we propose and experimentally demonstrate an approach to hide a high-resolution grayscale image in a square laser beam with a size of less than half a millimeter. An image with a pixel size of 300 × 300 nm is encoded into the spatially variant polarization states of the laser beam, which can be revealed after passing through a linear polarizer. This unique technology for hiding grayscale images and polarization manipulation provides new opportunities for various applications, including encryption, imaging, optical communications, quantum science and fundamental physics.

Highlights

Images consisting of optical patterns with spatially varying intensity or color profiles can be perceived by human eyes or cameras
Unlike optical holograms[1,2,3] and recently demonstrated color images in terahertz metasurfaces[4], for which the information is encoded in the amplitude profile of the light beam, the image here is hidden in its polarization profile
A grayscale image is hidden in the structured beam with a spatially variant polarization profile, which is realized by a reflective metasurface illuminated by a laser beam at normal incidence

Summary

INTRODUCTION

Images consisting of optical patterns with spatially varying intensity or color profiles can be perceived by human eyes or cameras. The first experimental demonstration of hiding a high-resolution grayscale image associated with a laser beam with a spatially inhomogeneous state of polarization is presented. This approach enables us to conceal the high-capacity information in the inhomogeneous polarization profile of the laser beam and transfer the hidden information along the propagation direction of the light. This simple approach may be applied to various fields, including encryption, imaging, optical communications, quantum science and fundamental physics

MATERIALS AND METHODS

RESULTS AND DISCUSSION

Experimental setup d

CONCLUSIONS