Programmable terahertz metamaterials with non-volatile memory

Abstract

Spatial light modulators (SLMs) exhibited the powerful capability of controlling the electromagnetic wave. They have found numerous applications at terahertz (THz) frequencies, including wireless communication, digital holography, and compressive imaging. However, the development towards large-scale, multi-level and multi-functional THz SLM encounters technical challenges. Here, we present an electrically programmable THz metamaterial consisting of an array of 8⊆8 pixels, in which the phase change material of vanadium dioxide (VO2) is embedded. After successfully suppressing the crosstalk from adjacent pixels, the THz wave could be modulated in a programmable manner. The switching speed of each pixel was on the order of 1 kHz. In particular, utilising the hysteresis effect of VO2, the memory effect is demonstrated. The THz amplitude of each pixel can be written and erased by individual current pulses. Furthermore, multi-state THz images could be generated and stored, with a retention time of more than 5 hours. This programmable metamaterial with memory effect can be extended to other frequency bands and opens a route for electromagnetic information processing.

Electrically addressable integrated intelligent terahertz metasurface

“…However, before applying coding sequences to alter the phase distribution of the SAM for beam deflection, we should first address thermal cross-talk between adjacent subarrays as it can deteriorate beam steering performance by obscuring the coding pattern. The thermal contact between the metasurface and hot plate is crucial for suppressing the thermal cross-talk ( 24 ). Here, we use a thermal paste with a conductivity of 14.3 W/(m·K) to decrease the thermal resistance and suppress the lateral thermal diffusion.…”

“…However, extending the phased array and programmable metasurfaces from microwave to THz frequencies encounters technological challenges due to the lack of electronic switches. In the THz regime, programmable metasurfaces that embed tunable materials, such as semiconductors (20,21), phase transition materials (22)(23)(24)(25), liquid crystals (26)(27)(28)(29)(30), and graphene (31,32), into subwavelength resonators, have been implemented. Despite the impressive progress, the major obstacle to realizing THz intelligent metasurfaces is the scarcity of low-cost sensors and pixelated phase modulators (33).…”

Terahertz Metamaterials for Free-Space and on-Chip Applications: From Active Metadevices to Topological Photonic Crystals

“…In 2022, programmable metasurfaces was realized by integrating with phase change materials actuated by current pulses [86]. The work shown in Figure 6(f) presents a programmable memory metadevice based on vanadium dioxide (VO 2 ) with 8 × 8 pixels operating as a terahertz spatial light modulator.…”

“…(e) Programmable LC-metasurface for terahertz beam steering[85]. (f) VO 2 -based programmable memory metasurfaces[86] (g) Cascaded metasurfaces for dynamic wavefront control[87].…”

Dual-color terahertz spatial light modulator for single-pixel imaging

“…The spatially modulated THz beam is collected by a bucket detector in the imaging setup, in which the spatial light modulators (SLMs) play an essential role. SLMs capable of dynamically modulating the phase 12 , amplitude 13 , and polarization of the light have already shown significant advantages in imaging, holography, and multiple-input multiple-output (MIMO) communications [14][15][16][17][18] . The commercially available SLMs operating in the optical regime, such as digital micromirror devices (DMD), can be directly adapted to the THz range for imaging by encoding a pumped beam incident on an optically active medium such as silicon and vanadium dioxide [19][20][21][22][23] .…”