Shanghai researchers unlock Elvis and moonwalks

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.

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

“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 different dimensions 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 will have great potential in many fields in the future, such as artificial intelligence, three-dimensional display, digital holographic microscopy, data storage, artificial neural networks and so on.

The team's research results were published in academic journal Nature Photonics on Tuesday.