Polarization and Frequency Multiplexed Terahertz Meta‐Holography

Abstract

Seeking effective and precise control over electromagnetic waves has always been an important focus in optics. Advances in nanofabrication technology have led to designer metasurfaces, which open up new possibilities by allowing almost arbitrary spatial distributions of optical properties to be realized. This study demonstrates a multiplexed meta‐hologram generating different images for different polarizations and different terahertz frequencies. By utilizing C‐shape bar resonators as the basic unit cells, simultaneous binary amplitude modulation and binary phase modulation in each pixel is realized. With polarization and frequency selective independent simultaneous control of amplitude and phase in every pixel, the proposed meta‐hologram makes use of all four fundamental properties of electromagnetic waves. Generation of holographic images of “C,” “F,” “T,” or “W” depending on polarization and frequency is demonstrated theoretically and experimentally. This approach, allowing for modulation of all characteristics of electromagnetic waves, paves the way for designing complex metasurfaces and metaholograms with multiplexed functionalities, which may have applications in multichannel communication and data storage.

Diffractive metalens: from fundamentals, practical applications to current trends

“…Multifunctional metasurface is a kind of metadevice that can execute concurrent tasks, such as multi-vortices beams generation [166][167][168][169][170], multiholography generation [32,97,[171][172][173], and other metasurfaces containing several functions [92,174,175]. Generally, the multifunctional metalens is also based on the phase manipulation of the EMWs.…”

Reflective chiral meta-holography: multiplexing holograms for circularly polarized waves

“…Benefiting from the rapid development and unique characteristics of metasurfaces, high-efficiency meta-holography, broadband meta-holography, and actively tunable meta-holography have been demonstrated by employing reflection-type 16 , 17 or dielectric 18 metasurfaces, geometric metasurfaces 13 – 16 , 18 , and stretchable metasurfaces 19 , respectively. Additionally, the ability to engineer the polarization, spectral and nonlinear properties of metasurface unit cells has enabled polarization-controlled holography 20 – 24 , multi-color holography 25 – 28 , and nonlinear holography 29 , 30 . However, independent generation of different holographic images for circularly polarized waves of opposite handedness remains challenging since the achiral resonators used in existing approaches inevitably contribute to both holographic images.…”

Dual-Focuses Metalens for Copolarized and Cross-Polarized Transmission Waves

“…In 2D situation, the effect of the losses of material becomes more obvious and cannot be ignored for normal materials. Even the PI material is a low loss material, and the loss tangent = 0.0057 of the polyimide [16] is taken into account in the following 2D structure simulation. It is important to mention that when the loss tangent is set to 0.0057, the phase spectrum of the crosspolarized transmittance of the WCRR is almost not shifted compared to the WCRR without loss (Figure 1(c)).…”

“…The abovementioned metalenses have the same characteristics where the cross-polarized waves are focused. Requirements such as dual-polarization focusing, or dual focuses for orthogonal polarization, which have more potential applications [13][14][15][16] for terahertz dualpixel imaging and dual-channel communication, could not be fulfilled by the existing metalenses.…”