(Nanowerk News) Refractive index – the ratio of the speed of electromagnetic radiation in a medium to its speed in a vacuum – can be modulated fast enough to generate photonic time crystals (PTCs) in the near-visible part of the spectrum, a new study published in the journal Nanophotonics demonstrates (“Time-refraction optics with single cycle modulation”). The study’s authors suggest that the ability to sustain PTCs in the optical domain could have profound implications for the science of light, enabling truly disruptive applications in the future.

PTCs, materials in which refractive index rises and falls rapidly in time, are the temporal equivalent of photonic crystals in which the refractive index oscillates periodically in space causing, for example, the iridescence of precious minerals and insect wings.

A PTC is only stable if the refractive index can be made to rise and fall in line with a single cycle of electromagnetic waves at the frequency concerned so, unsurprisingly, PTCs have thus far been observed at the lowest-frequency end of the electromagnetic spectrum: with radio waves.

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