Metamaterials at the University of Southampton and beyond

Abstract

At the University of Southampton, research on metamaterials started in 2000 with a paper describing a metallic microstructure, comprising an ensemble of fully metallic 'molecules'. In the years since then, metamaterials have evolved from an approach for designing unusual electromagnetic properties by structuring matter at the sub-wavelength scale to become a universal paradigm for active functional media with optical properties on demand at any given point in time and space. Metamaterials are now recognized as a promising enabling technology and one of the most buoyant and exciting research disciplines at the crossroads between photonics and nanoscience. Many 'made in Southampton' concepts have influenced the global research community, and we are now working in collaboration with our sister research centre in Nanyang Technological University, Singapore. In this article, I provide a historical overview of the metamaterials research field, from early studies to recent developments through the lens of the Southampton group, and discuss promising future directions.

Modeling of a Negative Refractive Index Metamaterial Unit-Cell and Array for Aircraft Surveillance Applications

“…A novel MTM unit-cell for satellite applications was proposed in [23]. The proposed MTM structure was developed on a 1.6mm thick FR-4 dielectric substrate with an overall dimension of 30×30mm 2 . For the parametric analysis and comparative study, different substrate materials such as lossy Polymide, Aluminum Nitride, and Rogers RT 6010 were utilized.…”

“…In contrast to natural materials, the MTM interacts with both light and sound waves in unanticipated patterns. The MTM has the potential to control the propagation of light inside waveguides and in free space [2]. Therefore, the ability to influence the propagation of EM waves and the outstanding features of MTM made it appropriate for various applications such as antennas, satellite communication, optical filters, invisibility cloaking, shielding properties, biosensors, sensor detection, signal multiplexing, holography, data processing, and battlefield communication [3][4][5][6][7][8][9][10][11][12][13].…”

Phase Change Metasurfaces by Continuous or Quasi-Continuous Atoms for Active Optoelectronic Integration

“…Therefore, a diversity of VO 2 -hybrid active metamaterials or metadevices emerged from the visible to THz and microwave range, e.g., tunable absorbers [ 83 ], THz modulators [ 81 , 99 ], THz switches [ 94 ], wavefront engineering [ 95 ] etc. In addition, a few review papers about VO 2 -hybrid active metamaterials had been reported [ 56 , 100 , 101 , 102 ]. However, due to the volatile nature of VO 2 , its metallic phase vanishes as long as the external stimuli are withdrawn.…”

“…By a close inspection of tunable resonance/transmission peak of the G 2 S 2 T 5 -hybrid plasmonic crystal, the relationship between the fraction of crystallization and baking time is quantitatively explored, as shown in Figure 2 b. In addition, another type phase change chalcogenide in the PCM family, G 3 S 2 T 6 , with lower mid-IR loss, was also introduced into the active metasurfaces based on the plasmonic resonances of Al antenna array [ 56 , 112 ], shown in Figure 2 c,d. A femtosecond laser pulse (800 nm, 50 fs and repetition rate of 960 Hz) was also used to trigger the reversible amorphous–crystalline phase transition for optically tunable transmission [ 112 ].…”

“…In principle, all those actively reconfigurable metasurfaces can be constructed by: (i) embedding active materials or components into hybrid device architectures, or (ii) directly structuring into thin films of active materials (e.g., graphene [ 32 , 33 , 34 ], phase change chalcogenides [ 35 , 36 , 37 ]). After a close inspection and classification, such active materials or mechanisms include the liquid crystal (LC) [ 38 ], MEMS [ 39 , 40 ], semiconductors [ 41 , 42 ], the 2D materials family represented by graphene [ 43 , 44 , 45 ], atomic-thin-layer direct tuning of 2D electron gas [ 46 ], conductive metal oxide (i.e., Indium Tin Oxide ITO) [ 10 , 47 , 48 , 49 ], magnetic or ferromagnetic materials [ 50 , 51 ], varactor arrays [ 52 , 53 , 54 ], and phase change materials (PCMs) [ 28 , 29 , 30 , 36 , 55 , 56 , 57 , 58 ]. Among these mainstream options, the LC-based methods are commonly used for conventional optical modulation, but with intrinsic obstacles in CMOS-compatibility and high-speed operations, especially for integrated photonics.…”