World record for laser transmission through the atmosphere

Scientists from the International Centre for Radio Astronomy Research (ICRAR) and The University of Western Australia (UWA) have set a world record for the most stable transmission of a laser signal through the atmosphere, as described in the journal Nature Communications.

Together with researchers from France’s National Centre for Space Studies (CNES) and Systèmes de Référence Temps-Espace (SYRTE) at Paris Observatory, the team set the world record by combining the Australians’ phase stabilisation technology — originally developed to synchronise incoming signals for the Square Kilometre Array telescope — with advanced, self-guiding optical terminals. Together, these technologies allowed laser signals to be sent from one point to another without interference from the atmosphere.

Lead author Benjamin Dix-Matthews, a PhD student at ICRAR and UWA, said the technique effectively eliminates atmospheric turbulence. “We can correct for atmospheric turbulence in 3D; that is, left-right, up-down and, critically, along the line of flight,” he said.

“It’s as if the moving atmosphere has been removed and doesn’t exist. It allows us to send highly stable laser signals through the atmosphere while retaining the quality of the original signal.”

The result is said to be the world’s most precise method for comparing the flow of time between two separate locations using a laser system transmitted through the atmosphere — and the research has exciting applications, according to ICRAR–UWA senior researcher Dr Sascha Schediwy.

“If you have one of these optical terminals on the ground and another on a satellite in space, then you can start to explore fundamental physics,” he said.

“Everything from testing Einstein’s theory of general relativity more precisely than ever before, to discovering if fundamental physical constants change over time.”

The technology’s precise measurements also have practical uses in earth science and geophysics. “For instance,” said Dr Schediwy, “this technology could improve satellite-based studies of how the water table changes over time, or to look for ore deposits underground.”

There are further potential benefits for optical communications, an emerging field that uses light to carry information. Optical communications can securely transmit data between satellites and Earth with much higher data rates than current radio communications.

“Our technology could help us increase the data rate from satellites to ground by orders of magnitude,” Dr Schediwy said.

“The next generation of big data-gathering satellites would be able to get critical information to the ground faster.”

Image credit: UWA’s rooftop observatory. Image credit: ICRAR.

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