Photonics

Where does 'photonics' comes from? The prefix ‘photon’, which describes the particles of light, was coined in 1926 by American physical chemist Gilbert N. Lewis. As with electronics, the 'art' of harnessing electrons, photonics is the 'art' of harnessing photons. Today it includes a series of scientific and technological applications, most of them in informatics and communication, but also in power generation, medical diagnosis, laser-based manufacturing, and of course, light emitting diode (LED) illumination and displays.

Fiber optics is one of the most successful mediums for telecommunication and computer networking, and looking at its incredible pervasiveness in those submarine cable maps should not surprise anyone. But the difference between optics and photonics has been a constant bone of contention among scholars. Optics, as stated in most treatises, is the science of vision whereas photonics is the science of light or, more precisely, photonics is a sub-discipline of optics. It would be out of place to weigh all these academic issues here. We would rather stick to seventeenth century tradition according to which optics cover the entire doctrine of sight and light, because it assumes a convergence.

From Cloak of Invisibility to Optical Traps

A case that was widely reported by the media a few years ago was that of the invisible cloak, a recurring theme in fairy tales and science fiction. If you break down the story, you will discover the world of photonic metamaterial, or manufactured stuff that can bend light in precisely curved paths, exciting an optical phenomena called negative refraction. But it was no more than a curiosity, attracting only LARP players.

Something like optical traps, by the other hand, have its uses. These scientific instruments 'tame' the momentum carried by a laser beam to manipulate microscopic objects (as proteins and RNAs), moving and holding them as 'tweezers', for which reason they are also called optical tweezers. Invisible cloak technology comes in handy, because researchers can now combine traps with 3D negative refraction flat lenses (fondly known as 'perfect lens'), ensuring a better focus.

Rural Senses

Measuring up through laser-based sensors is an applicable field of photonics and much has been done in the agricultural sector. Agri-Photonics, a field of precision farming and environmental management, is growing stronger inside European farmers circle. One of its most relevant tools, chiefly used to characterize leaf inclination distribution, is LiDAR (Light Detection and Ranging), an optical remote sensing method that, through pulsed laser beams, measures properties of reflected light in order to obtain information about scanned targets. It works similarly to radar technology, but instead of emitting radio waves, it reads the time difference between the emission and the detection of a laser beam. That is a somewhat backwoods kind of enlightenment...

What Lies Ahead

Green Photonics

As the name says, its main goal is the sustainable use of light, conserving energy and reducing emissions. Thus other photonics methods have been devised, heeding on how to reduce the cost of optical-to-electrical-to-optical conversions as environmentally safe as possible. Let us say that, in the field of integrated circuits, the victory of silicon, today its predominant component, is not completely assured. If there is an opening for a possible substitute, the photonic integrated circuits (PICs) should be a serious match, and there is nothing to prevent factors like sustainability to become a key driving force for their development.

White Photonics

The electromagnetic spectrum, or the band of light visible to the human eye, spans from the deep-ultraviolet to the mid-infrared region and, if our school days serve us right, white light is the mixture of all the colors of the rainbow. Scientists and researchers need light sources with a wide range of colors for many applications. It is possible, for instance, to stop the evolution of tumors with fluorescent proteins, if the cancer cells are irradiated with lights of different colors. The problem is that, when filtering a specific band, there is loss of brightness. But when beaming a low-energy infrared laser pulse through a photonic crystal fibre (PCF) it can block, or let pass, certain wavelengths; a technique named spectral selectivity. These fibres can also produce intense white light and may be the source, in a near future, of white organic light-emitting materials and devices (WOLEDs).