Dual‐broadband highly efficient reflective multi‐polarisation converter based on multi‐order plasmon resonant metasurface

Abstract

In this study, a dual‐broadband reflective polarisation converter with high efficiency for both linear‐to‐linear and linear‐to‐circular polarisations based on a metasurface is proposed. Owing to the characteristics of strong anisotropy and multi‐order plasmon resonances, the proposed polarisation converter can rotate an y/x polarised electromagnetic wave to its cross‐polarised (x/y) direction in the lower frequency band of 7.74–14.44 GHz (a fractional bandwidth of 60.4%) with over 0.9 polarisation conversion ratio. Besides, the proposed structure can also convert a linearly polarised incident wave to a circularly polarised one after reflection in the higher frequency band of 14.95–17.35 GHz (a fractional bandwidth of 14.9%). The performance in the two bands can be controlled separately by altering the proper parameters of the structure. Numerical analysis is used to predict the polarisation states of the proposed polarisation converter. Moreover, the physical mechanism of multiple resonances is discussed based on surface current distributions. A prototype of the polarisation converter is fabricated and measured. A reasonable agreement between the experiments and simulations is obtained. The design has a simple and scalable geometry, and is a good candidate for polarisation control devices in microwave, terahertz and optical frequency regions.

Design of Low Profile Multiband Reflective Polarization Converter for Both Linear and Circular Polarized Waves

“…As mentioned earlier, at this frequency band, linearly polarized wave is converted to circularly polarized wave. In the surface current distribution plot, two orthogonal components of the surface currents are clearly observed which indicate the circular polarization behavior of the reflected wave [25]. In Figs.…”

Active Metasurface-Based Reconfigurable Polarization Converter With Multiple and Simultaneous Functionalities

“…5 (Inset), we define the /0 axes along the ±45 directions in the xy plane. Electric field 23 ⃗ 4 5 of the y-polarized incident wave in this system is given by [14]:…”

“…The P component of the induced magnetic field is perpendicular to the incident electric field, hence P never leads to ypolarization. But the P component of the induced magnetic field is parallel to the incident electric field, hence an incident y-polarized incident field is converted into an x-polarized reflected field [14]. From Fig.…”

“…Again, as shown in Fig.7(b), the net current flow consists of two orthogonal current paths, (F ,H+HIJ ) and 2F ,H+HIJ 5, (i) current flow in the up-down direction (F ,H+HIJ ) and (ii) current flow consists of two orthogonal current paths, (F ,H+HIJ ) and 2F ,H+HIJ 5, (i) current flow in the up-down direction (F ,H+HIJ ) and (ii) current flow in the left-right direction (F ,H+HIJ ). Similarly, the flow directions are nearly orthogonal to each other which gives LP-CP conversion[14]. Further, the surface current distribution on the top metal and ground layers are reported in Fig.8, at two resonant frequencies for the LP -OLP conversion when the diodes are ON.…”

“…However, the capability of the designs [4]- [10] are limited, as they can offer only a single functionality (either LP-OLP or LP-CP) at a time. Although simultaneous conversion (LP-OLP and LP-CP) is achieved [11]- [14], such structures exhibited fixed functionalities and, thus, the operating conversion states (i.e., LP-OLP or LP-CP) could not be selected after fabrication. To mitigate these issues, switchable polarization converters were introduced [15]- [20].…”