How do photonic crystals control the movement of light?

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The powers of 10 — nanotechnology Examples from biological and mechanical realms illustrate various “orders of magnitude” (powers of 10), from 10⁻² meter down to 10⁻⁷ meter.

Photonic crystals control the movement of light by utilizing a periodically varying dielectric constant, such as an array of semiconductor posts surrounded by air. When the size and periodicity of these structures approach the wavelength of light, they function analogously to the quantum mechanical rules that govern electron motion in semiconductors.1

By creating these periodic structures in two or three dimensions, researchers can establish bandgaps that define and limit the propagation of photons based on their energy and wavelength. This allows for precise manipulation of light on an extremely small scale, including the ability to:1

Confine light: Trapping photons within specific regions of the structure.1
Steer light: Directing the path of light through the material.1
Separate light: Sorting photons by their specific wavelengths.1

These capabilities are currently being explored to develop advanced technologies, such as near-thresholdless lasers and improved systems for optical communications and chemical sensing.1