Trapping light using Tetris-like clusters of crystals

Humans have a natural inclination to love light and its diverse spectrum of colours. Ancient civilisations have for centuries been mystified by the colourful conundrum that precious gems, butterflies’ wings and peacocks’ feathers provide when placed under the sun. Only during the last centuries have we truly begun to understand their behaviour. 

These beautiful optical materials are called photonic crystals, and have a well-defined periodic structure that only specific photons (or light particles) can pass through. Because white light is composed of a wide range of wavelengths, these crystals act as filters letting us see only certain colours. 

We barely knew the potential use of these photonic crystals until 1987. Eli Yablonovitch (who was still working in Bell Communications) and Sajeev John (who was still in Princeton University) were able to create artificial photonic crystals similar to those produced in nature, except theirs were ceramic-based materials drilled to form three intersecting arrays of holes. 

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