| FEATURES & INNOVATIONS |
resonant metallic nanostructures,” comments Kuznetsov. Furthermore, metals commonly used for plasmonics such as silver and gold are incompatible with standard methods for manu- facturing semiconductor components, making them difficult to produce.
A quiet revolution But now a quiet revolution is underway in this area. The focus is shifting away from metals and toward electrically insulating and partially insulating materials known as dielectrics and semiconductors, which are ‘optically dense’ so that light travels considerably slower in them than in air. Examples of such materials include the semiconductors silicon, germanium and gallium arsenide, and titanium dioxide. “The shift from metals to dielectrics is
already happening,” says Kuznetsov. “Many leading teams in plasmonics have already started to work with resonant dielectric nanostructures.” Though still in its infancy, the transition has
revealed many benefits. “After the demonstra- tions of resonances in dielectric nanoparticles in 2012, the field took off,” says Kuznetsov. “Many advantages over conventional plasmonics have now been found.”
Leading the way Kuznetsov and his team at A*STAR are at the vanguard of this revolution. They employ a three-pronged approach. “In many cases, we generate a theoretical concept, show it in simu- lations and then demonstrate it experimentally. However, sometimes the reverse process occurs — unexpected experimental observations lead to theory development to provide their physical understanding,” explains Kuznetsov. The team members have realized some
remarkable firsts in this young field. Physicist Boris Luk’yanchuk started the ball rolling in 2010 when he and colleagues in Germany published a seminal paper showing that, theo- retically, silicon nanoparticles with sizes ranging from 100 to 200 nanometers might have both strong electric and magnetic resonances at visible-light frequencies — a low-loss alternative to plasmonic nanostructures1
. In a subsequent
paper, Luk’yanchuk, together with researchers in Australia, proposed novel metal–dielectric hybrid structures where light could propagate due to interactions of magnetic moments, which is not possible in chains of metallic particles2 Finally, in 2015, the A*STAR group showed that
.
www.astar-research.com A*STAR RESEARCH 43
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