Shanghai team discovers way to send many holographs in one file

IMAGINE a scenario like this: You and your friend receive the same encrypted holographic file. Using different “light keys” to decode the file, you see Michael Jackson singing and doing the moonwalk while your friend sees Elvis Presley’s rock and roll.

Holographic technology developed by a research team at the University of Shanghai for Science and Technology led by professor Min Gu, a foreign member of the Chinese Academy of Engineering, can make that a reality.

Traditionally, one hologram contains only one picture, but the new technology make it possible to record more pictures without expanding the memory, greatly increasing the storage capacity.

Fang Xinyuan, a member of Gu’s team, said it had employed twist light beams with orbital angular momentum as an information carrier.

“Light beams with different orbital angular momentum twist in diverse manners as they travel in space. Twist light in different propagation paths can carry multiple information in holography. The message can be only interpreted by the specially designed twist light key.”

Therefore, Fang said, using different twist light beams with different orbital angular momentum, they can transmit or store different encrypted holographic information in the same space. And using the light that encrypted the information, they can unlock the information.

Fang said the team has designed 100 kinds of twist light beams, which means they can transmit or save information in 100 dimensions in the same space, increasing the optical transmission channel capability or memory 100 times.

“With traditional holographic techniques, it’s very difficult for individuals to get a holographic display like the scenario we mentioned, which is the trend for technology development. The new breakthrough will make it possible as it has paved the way for the first ultra-broadband holographic technique in the world,” said Gu.

“This high-capacity holographic technology will cope with the imperious demand on the information-processing ability by the coming era and also improve the security in daily data transmission.”

Gu said orbital angular momentum holography has great potential in many fields, such as artificial intelligence, 3D display, digital holographic microscopy, data storage and artificial neural networks.

The team’s research results were published in Nature Photonics yesterday.