Dynamical control on helicity of electromagnetic waves by tunable metasurfaces

Abstract

Manipulating the polarization states of electromagnetic (EM) waves, a fundamental issue in optics, attracted intensive attention recently. However, most of the devices realized so far are either too bulky in size, and/or are passive with only specific functionalities. Here we combine theory and experiment to demonstrate that, a tunable metasurface incorporating diodes as active elements can dynamically control the reflection phase of EM waves, and thus exhibits unprecedented capabilities to manipulate the helicity of incident circular-polarized (CP) EM wave. By controlling the bias voltages imparted on the embedded diodes, we demonstrate that the device can work in two distinct states. Whereas in the “On” state, the metasurface functions as a helicity convertor and a helicity hybridizer within two separate frequency bands, it behaves as a helicity keeper within an ultra-wide frequency band in the “Off” state. Our findings pave the way to realize functionality-switchable devices related to phase control, such as frequency-tunable subwavelength cavities, anomalous reflectors and even holograms.

Single layered swastika-shaped flexible linear-to-circular polarizer using textiles for S-band application

“…These polarizers are fundamentally formed using frequency‐selective surface unit cells in the form of loops, meander lines, dipoles; and also with metamaterial‐based structures or resonators. Their operating frequencies include the Ka‐band, X‐band, and several other frequency bands to cater different applications, including space application. However, very few researches are focused on designing linear‐to‐circular polarizers for S‐band applications, except for our initial work in Ref .…”

Dual-functional active frequency selective surface using parallel feeding configuration and its equivalent circuit model

“…In addition, by putting the multifunctional structures on the top of a ground plane, interesting polarization transformation functions could be obtained. Indeed, the two components of an φ = 45° impinging linear polarized wave can be reflected with a positive or negative phase or even with a 90° phase thus providing all polarization states in reflection …”

Compact Multi-Band Mimo Antenna With Improved Isolation

“…In [18], MTMs are used for reducing mutual coupling. In [19], an antenna which resonates at five bands 3.13 GHz: S-band (2-4 GHz); 8.89 GHz and 10.69 GHz: X-band (8-12 GHz); 16.79 GHz: Ku-band (12)(13)(14)(15)(16)(17)(18); 20.37 GHz and 26.06 GHz: K-band (18-27 GHz); 30.13 GHz and 36.26 GHz: Ka-band (27-40 GHz) is discussed. In [20], the reduction of mutual coupling using parasitic element is discussed in detail.…”