A new method for mass-assembling semiconductors into fusilli pasta shapes could one day lead to moving holograms projected right from your smartphone.
Since their invention in the 1960s, static holograms have found applications in everything from data storage to credit card authentication. But holographic moving images are still stuck in the realm of science fiction.
Now Nicholas Kotov at the University of Michigan and his colleagues hope to change that using spiral semiconductors.
To make a hologram, information about an object is recorded into a light-sensitive material, such as photographic film or plates. When it is lit in just the right way – often with lasers – the recorded pattern is recreated in three-dimensional space.
Regular holograms are frozen light waves. Getting them to move requires a material that can twist light in specific ways – say, get them to change phase or polarisation very quickly – so they act, in essence, like a flip book.
Semiconductors are good materials for this sort of thing because they are easy to work with and some can emit light, but they typically take the shape of sheets or wires. However, Kotov realised that if they could be fabricated in spiral shapes at the nanoscale, they could act as a waveguide: light passing through would naturally follow the twists in the material.
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