Technique Makes Holograms Highly Efficient, Secure

Harvard University researchers have programmed polarization into compact holograms, enabling devices to produce different images based on the polarization of incident light.

The researchers say the technology could be used to improve anti-fraud holograms, as well as those used in entertainment displays.

"By using nanotechnology, we've made holograms that are highly efficient, meaning that very little light is lost to create the image," says Harvard professor Federico Capasso.

The new holograms work like traditional holograms, but the image produced depends on the polarization state of the illuminating light, adding an extra degree of freedom in design for versatile applications.

The researchers built silicon nanostructured patterns on a glass substrate, which act as superpixels that each respond to a certain polarization state of the incident light. More information can be encoded in the hologram by designing and arranging the nanofins to respond differently to the chirality of the polarized incident light.

"By using different nanofin designs in the future, one could store and retrieve far more images by employing light with many states of polarization," Capasso says.

In addition, he notes the system is so compact it has applications in portable projectors, three-dimensional movies, and wearable devices.

From Harvard University
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