Optical Steganography via Programmable Anchoring Boundary of Soft Materials

Abstract

Engineering the properties of light with multi‐channel planar elements can produce independent spectral response, and has formed the solid basis for image steganography techniques, which holds great promise for applications including information storage, optical encryption, and anti‐counterfeiting. However, most of the recently reported steganography systems suffer from limited size, sophisticated fabrication, and finite degree of freedom in encoding and decoding process. Herein, a versatile image steganography system based on soft material is proposed. The polarization and intensity of transmitted light are modulated by programing the anchoring boundary of liquid crystals, allowing arbitrary independent images multiplexing in single‐size element with high fidelity. Specifically, the stimuli‐responsiveness of liquid crystals endows the platform with a new degree of freedom to manipulate the transmitted spectrum dynamically, further sketching a prospective framework toward a new type of steganography with fascinating tunability. The proposed strategy sheds new light on multifarious display system by harnessing the stimuli‐responsiveness of soft materials, leading to promising applications in information storing, image steganography, anti‐counterfeiting, and multilevel encryption techniques.

Dynamically Tunable Structural Colors Enabled by Pixelated Programming of Soft Materials on Thickness

“…Such unique electric-field-dominated, perspective-dependent characteristics may inspire multiple anti-counterfeiting techniques. [42,48] As mentioned previously, LCs are also sensitive to thermal factors in addition to the electric field. [49] In this study, a dynamically tunable structural color with a thermal response was developed.…”

“…Herein, we present a facile method to realize dynamically tunable structural colors enabled by the pixelated programming of soft materials on thickness. Pixelated photoresist microarrays with different thicknesses were obtained via a digitalized lithography technique, [41,42] enabling delicate control over the thickness of NLCs and providing a new degree of freedom for modulating the transmission spectrum. Thus, arbitrarily desired patterns with multiple colors coexisting in the visible range are demonstrated without complex material components or additional processing approaches.…”

Sub-Diffraction Readout Method of High-Capacity Optical Data Storage Based on Polarization Modulation

“…Here, we introduced the number error rate to evaluate the impact of κ on the resolution, which is the minimum distance between the two adjacent data points that can be read out without any decoded number errors, as shown in Figure 7 g. We found that the resolution increases with the κ values. Normally, the κ value depends on the polarization-selective feature of the storage mediums, for example, the κ of the azo-dye chromophores is 2 [ 43 , 44 , 45 , 46 , 47 ], for gold nanorods, it is nearly 5 [ 11 , 20 ], and for liquid crystal, it is more than 10 [ 48 ]. Therefore, for κ = 2, the resolution of the sub-diffraction method is 150 nm; when κ = 5, the resolution can achieve 90 nm, even up to 70 nm at κ = 10.…”

“…We found that the resolution increases with the κ values. Normally, the κ value depends on the polarization-selective feature of the storage mediums, for example, the κ of the azo-dye chromophores is 2 [43][44][45][46][47], for gold nanorods, it is nearly 5 [11,20], and for liquid crystal, it is more than 10 [48]. Therefore, for κ = 2, the resolution of the sub-diffraction method is 150 nm; when κ = 5, the resolution can achieve 90 nm, even up to 70 nm at κ = 10.…”

Multiple degrees‐of‐freedom programmable soft‐matter‐photonics: Configuration, manipulation, and advanced applications

“…Besides, nematic LCs can precisely response to the electric current and thus they are excellent responsive materials to control the propagation of light. [17] Traditionally, nematic LCs are used in the manufacturing of LCDs, in which the LC directors align homogeneously without changing their local orientation. At present, nematic LCs are still one of the most attractive soft materials in novel optical elements that require complex distribution of directors, which we will discuss in details in the following chapters.…”