Liquid crystal integrated metadevice for reconfigurable hologram displays and optical encryption

Abstract

The ultimate goal of metasurface research in recent years is to apply metasurface to reality applications and improve the performance compared to its counterpart, namely conventional optical elements with the same function. Inspired by the application of electrically addressing spatial light modulator (EA-SLM) and based on the binary holographic algorithm, here we propose a reconfigurable metadevice integrated with the nematic liquid crystal (NLC). The smart metadevice directly uses the subwavelength antennas as the main contributor to the phase accumulation instead of the NLC layer. By applying different electrical modulation patterns on the NLC, the metadevice can realize the function of dynamic holographic display as traditional SLMs but features in smaller size, higher resolution and lager field of view. In addition, we improved the existing computer-generated hologram algorithm to generate three holograms with quantitative correlation and also propose a new optical encryption method based on our metadevice. The encryption method needs four elements in total to decrypt and can fully meets the requirements of the various encrypted content. We believe such metadevice paves the way for the new generation of micro-optical display and optical encryption devices.

Tunable metasurfaces towards versatile metalenses and metaholograms: a review

“…External stimuli can be classified as electrical or non-electrical stimuli. Therefore, this section presents electrically tunable [149][150][151][152][153][154][155] and non-electrically tunable 34,[156][157][158][159][160][161][162][163][164] methods to tune metaholograms.…”

“…5 new optical encryption method exploits an improved computergenerated holography (CGH) algorithm to generate holograms that have quantitative correlation. 153 A nematic LC layer realizes the function of dynamic holographic display. One set of electrical modulation patterns acts as encryption keys, and the receiver decrypts the message using both cipher text and a table transferred holographically.…”

“…Research goals Multi-, varifocal length Storing multiple images 54,[129][130][131][132][133][134][135][136][137][138][139][140][141][142] Visualized sensing (thermal, chemical, etc.) [155][156][157][158][159][160][161][162] Optical encryption [140][141][142] Common stimuli Electrically tunable LC [76][77][78][79][80][81][82][149][150][151][152][153][154][155] Polarization (circular and linear polarization) [69][70][71][72][73][74][75][129][130]…”

Mid‐Infrared Dynamic Wavefront Transformer Based on a Two‐Degrees‐of‐Freedom Control System

“…Recently, metasurfaces combined with SLMs technologies have been applied to tunable devices with complex output wavefronts with high spatial resolutions and control freedoms simultaneous but at the cost of fabrication difficulties. [32][33][34] The 6 kHz modulation speed of demonstrated wavefront transformer, which is limited by the bulky size of metasurface B and the control system's intrinsic resonance frequency, is the fastest mechanical beam steering demonstrated so far in our knowledge. Besides, the modulation speed of the wavefront transformer can be further pushed to 100 kHz using the piezo-actuation system or even MHz by microelectromechanical (MEMS) systems, as discussed in Figure S4 (Supporting Information).…”

Single Pixel Imaging Key for Holographic Encryption Based on Spatial Multiplexing Metasurface

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In addition, metasurface holography can encode multiple images on a single metasurface by multiplexing methods, which can improve the information capacity and further realize the applications of encryption, anti-counterfeiting with higher security and fidelity. [19][20][21][22][23][24] For example, by modulating different incident and output polarization states, metasurface can realize different encrypted images under different polarization channels. [25][26][27][28][29] Besides, amplitude can also be used as an important degree of freedom in holography, especially the simple binary amplitude modulation can achieve satisfactory holographic reconstruction, which provides a direction for metasurface holographic encryption.…”