Researchers have developed a new type of nanophotonic chip that can manipulate the spin as well as the twist of light with unprecedented control.

This technology pushes us one step further towards optical computers, as well as a number of other high-speed optical technologies, and could even help scientists understand more about gravitational waves and black holes.

Although we usually imagine a beam of light travelling in a straight line, light also spins and twists around its own optical axis, which is measured by something called angular momentum (AM).

Researchers have spent years trying to manipulate the AM of light, so they can create parallel beams of light in optical fibres and greatly increase the bandwidth of data travelling through them - a process known as ‘multiplexing’.

But to do this, they need to create chips that can control the AM of light, and in the past, they’ve struggled to get the technology small enough, seeing as no natural materials have the capacity to sense and change how the light twists.

Now, researchers from Swinburne University of Technology and RMIT University in Australia have managed to create a tiny chip that can manipulate twisted light better than ever before, which they hope will be able to control both the spin angular momentum (SAM) and the spatial distribution, called orbital angular moment (OAM).

"By designing a series of elaborate nano-apertures and nano-grooves on the photonic chip, our team has enabled the on-chip manipulation of twisted light for the first time," said the project leader from RMIT University, Min Gu. "The design removes the need for any other bulky interference-based optics to detect the AM signals."

The chip works because the nano-grooves on the surface move the beams into different plasmonic fields. This splits and sorts the different AM signals so they can be controlled and analysed, without loss of information.

"If you send an optical data signal to a photonic chip it is critical to know where the data is going, otherwise information will be lost," lead author and researcher at Swinburne University of Technology, Haoran Ren said. "Our specially-designed nanophotonic chip can precisely guide AM data signals so they are transmitted from different mode-sorting nano-ring slits without losing any information."

The researchers are hoping this technology could be used to investigate how black holes interact with each other, since the movement of black holes can transmit OAM light associated with gravitational waves. "An unambiguous measuring of the OAM through the sky could lead to a more profound understanding of the evolution and nature of black holes in the universe," Gu said.

The new chip could also be used to create new optical technologies such as better optical fibre and encryption methods. "Our discovery could open up truly compact on-chip AM applications such as ultra-high definition display, ultra-high capacity optical communication and ultra-secure optical encryption," Gu said.

Bring on better definition displays, faster internet, and more secure connections, we say. We’re really excited to see where this technology can take us.

This research has been published in Science.

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