Welcome Physics World  September 2020

Going meta

Efficient focusing. (Courtesy: Boubacar Kanté)

Natural phenomena don’t fit into tidy disciplinary boxes, so it’s not surprising that some of the most productive areas of research sit at the interface between fields. A case in point is the development of optical metamaterials – that is, materials and surfaces that are engineered on the micro- or nano-scale to have specific optical properties. As the articles in this Physics World Optics & Photonics Briefing show, such metamaterials are thinner and lighter than traditional lenses, and can be constructed in such a way as to banish chromatic aberration, filter out undesirable wavelengths, dynamically change the profile of a laser beam, or undercut the diffraction limit.

Other articles in this Briefing focus on exciting cross-disciplinary developments in the field of quantum optics. Experiments that cool tiny glass spheres to their motional ground state, measure the effects of rotation on a single quantum spin, and – most astonishingly of all – capture a “snapshot” of a quantum system during a measurement could not have happened without advances in laser technology.

At present, these experimental feats are solidly in the realm of basic research. However, history shows they are unlikely to stay there for long. Just ask Martin Booth and Patrick Salter, whose research on adaptive optics led them to start Opsydia, a company that uses lasers to create microscopic marks inside gem-quality diamonds and other transparent materials. Similarly, Shangran Xie and colleagues at the Max Planck Institute for the Science of Light usually spend their time developing applications for hollow-core photonic crystal fibres, but then it occurred to them that one of these fibres’ perennial bugbears – scattered light – could make a nifty way of monitoring air pollution.

Of course, not all interdisciplinary research is as well established as, say, biomedical optics. Sometimes, photonics experts find themselves in territory so uncharted that it doesn’t even have a settled label yet – in which case they get the fun of naming it. A case in point is “phoamtonics”, a new micro-discipline concerned with the optical properties of low-surface-area materials known as Weaire–Phelan foams. Such foams can act as optical filters, so in principle it might be possible to use them to transport and manipulate light – perhaps even as a replacement for conventional fibre-optic cables. Personally, I don’t see it happening anytime soon – but then, a few decades ago not many people would have envisioned metamaterials replacing glass lenses either.