Light-controlled metasurface with a controllable range of reflection phase modulation

Abstract

The reconfigurable metasurface (MS) with tunable electromagnetic scattering properties has had an impact on innovative communication applications. However, the widely studied MS controlled by direct-current (DC) bias requires complex physical control circuits in array wavefront encoding, while the light-controlledapproach of the light-controlled MS MSwith a controlladoes not. In this paper, we report a newble modulation range of reflection phase,and its unit is composed of a reflection phase element based on the varactor and an opticalinterrogation network (OIN) based on the photoresistor so that the phase distribution of eachMS unit could be independently programmed optically. To illustrate our approach, a 2-bit reflection phase MS with 10 × 10 units was fabricated and tested to achieve pencil beam scanning and orbital angular momentum (OAM) beam at microwave frequencies. The simulated and measured results verify the feasibility of the proposed design. Furthermore, all the OINs on the MS are connected in parallel and powered by the same DC voltage source, which simplifies the difficulty of array expansion in MS design with a large-scale array.

Optoelectronic Metasurface for Free-Space Optical–Microwave Interactions

“…Such an important property makes it promising to find many applications in advanced EM manipulations and multi-domain signal processing. The optoelectronic metasurface can be used to realize optically driven and optical-sensing microwave metasurfaces and devices that are capable of achieving wireless-control functions, such as cloaking, beamforming, and nonlinear generation. − Compared with the traditional electrically controlled metasurfaces, the optically driven metasurfaces enable remote control of microwaves by spatial light, which can effectively mitigate the complexity of the bias network and the DC-EM crosstalk. Moreover, the optically driven metasurface offers an efficient interface to link light and microwave in free space, providing a low-profile platform to realize the wave-based direct conversions of optical and microwave signals, which is fundamentally important to the optoelectronic hybrid wireless communications, quantum networks, and relevant applications.…”

A 2D-programmable and Scalable RIS Remotely Controlled via Digital Infrared Code

“…On the contrary, the patches were placed on the front side. For isolation of the two sides, resonant traps (RF chokes) can be used at the corresponding vias [20], [29], [30]. Embedded biasing circuits can contain distributed controllers placed in every unit cell or usually a group of unit cells.…”

“…The RIS had a centralized control unit with several bias voltage combinations pre-coded in FPGA enabled when receiving coded signals from a remote infrared transmitting circuit. Recently, a light-controlled RIS operating at 6.375 GHz integrated with photoresistors and varactors has been proposed, which can independently obtain a controllable range of reflection phase modulation on each unit [20]. A full 2D phase encoding capability was first achieved in [20] by integrating a photoresistors-based circuit on the back side of each unit cell and using the dynamically reconfigurable light field illumination created using a liquid-crystal display placed behind the RIS.…”

“…Recently, a light-controlled RIS operating at 6.375 GHz integrated with photoresistors and varactors has been proposed, which can independently obtain a controllable range of reflection phase modulation on each unit [20]. A full 2D phase encoding capability was first achieved in [20] by integrating a photoresistors-based circuit on the back side of each unit cell and using the dynamically reconfigurable light field illumination created using a liquid-crystal display placed behind the RIS. This approach simplifies scaling the reflective aperture of the RIS due to independent analog-type biasing of identical unit cells all powered by the same DC voltage.…”

“…Most of them consist in loading patches or other resonant printed metal shapes backed by a grounded dielectric substrate with biased varactor diodes or positive-intrinsic-negative (PIN) diodes. Varactor diodes allow either uniform phase tuning [16], [17] or discrete phase switching [18]- [20] depending on the capabilities of the control circuits. PIN diodes are useful only for RISs with discrete phase states.…”