One of the important challenges in electrical engineering is to make smaller and more complicated electrical circuits. In this pursuit, University of Pennsylvania researchers have taken a drastically different route — they replace electricity with light, which would enable them to go to much smaller dimensions of circuitry.

A recent paper in the journal, Physical Review Letters, brings this advancement to the public eye. Dubbed “metatronics” by the discoverer Nader Engheta, who is a professor in the electrical engineering department of University of Pennsylvania, this is a nascent field in electrical engineering and the discovery described in the paper is a milestone in this field.

The “meta” in metatronics is inspired by metamaterials which refers to nanoscale patterns and structures embedded in materials and allowing manipulation of incident waves. In metatronics, cross-sections of nanorods and the spaces between them form patterns that mimic the behaviour of resistors, capacitors and inductors.

These patterns respond to light the way capacitors, resistors and inductors do to electricity.

In 2005, Engheta’s group published a theoretical paper outlining how optical circuit elements can work, because, after all, electric circuits and optics both obey Maxwell’s equations. What was proposed theoretically by them was realised in an experiment in 2012, with their first demonstration of “lumped” optical circuit elements using silicon nitride. This was published in the journal, Nature Materials. While this was in itself a stunning experiment, the light they could manipulate was in the mid-infrared region and not in the near-infrared region where most fibre optic devices work.

Now the group has come out with a paper in Physical Review Letters in which they report that they have built the first metatronic circuit elements from indium tin oxide which work for near-infrared light. This again, is in the domain of functioning of fibre-optic devices and much closer to being exploited as technology.

The future for this discovery is rich as there remains a lot to be done before this can be made viable. Of course, the technology lying in wait is exciting to say the least.

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