GOING CHIRAL

How the twist of a photon can make all the difference

- Ian Evenden

Chiral – pronounced Kai-ral after the Greek letter Chi – is not a word Hideo Kojima made up while developing Death Stranding. Sam Bridges’ Chiral Network is complete nonsense, obviously, but chirality is a common property of molecules and even light that occurs naturally and, with a bit of help from us, is helping create the electronics of the future.

Consider the mantis shrimp, if you dare. These predatory crustaceans come in two types: the smashers with a pair of legs adapted as clubs, and the spearers who have evolved barbed tips to their appendages. What they both have in common are incredible eyes, with up to 16 types of photoreceptor cell (humans bumble around in relative darkness with only three) some of which can detect circularly polarised light, which they might possibly use to signal to one another. This circular polarisation means that while the light waves continue to move in a straight line, their electromagnetic fields rotate perpendicularly (at a right angle) to this direction. Photographers will know this from the circular polarising filters that can be screwed onto a camera lens to increase colour saturation and contrast in a scene at the cost of a little brightness.