Light is all around us, essential for one of our primary senses (sight) as well as life on Earth itself. It underpins many technologies that affect our daily lives, including energy harvesting with solar cells, light-emitting-diode (LED) displays and telecommunications through fiber optic networks.

The smartphone is a great example of the power of light. Inside the box, its electronic functionality works because of quantum mechanics. The front screen is an entirely photonic device: liquid crystals controlling light. The back too: white light-emitting diodes for a flash, and lenses to capture images.

We use the word photonics, and sometimes optics, to capture the harnessing of light for new applications and technologies. Their importance in modern life is celebrated every year on 16 May with the International Day of Light.