The research team, led by UNSW Professor Ned Ekins-Daukes and Dr Michael Nielsen, and including Professors Michael Fuhrer and Stefan Maier from Monash University and Imperial College London, have so far managed to send data at about 100 kilobytes per second in lab experiments.

But they believe speeds could reach gigabytes or even faster with further improvements to the emitter technology.

“Data is so ubiquitous nowadays, but we’re not necessarily coming up with new ways to protect that data,” said Dr Michael Nielsen, lead author from UNSW's School of Photovoltaic and Renewable Energy Engineering.

“We do have encryption methods, but at the same time we’re always having to create new encryption methodologies when bad actors find new decryption strategies.

“But if someone doesn’t even know the data is being transferred, then it’s really very hard for them to hack into it. If you can send information secretly then it definitely helps to prevent it being acquired by people you don’t want to access it.”

The new process, described in a paper published in Nature Publishing Group’s Light Science and Applications, utilises the special effect of negative luminescence from LEDs operating in the mid-infrared part of the light spectrum. 

Everything gives off a faint glow of heat in the infrared, which we normally can’t see – unless using special thermal cameras.

"What makes negative luminescence so interesting is that it makes that glow look darker instead of brighter. By way of a comparison, it would be like a flashlight that can somehow go darker than ‘off’," added Dr Nielsen.

"While that’s not possible to achieve with visible light, certain materials can create this ‘negative light’ effect in infrared, which is what the research team are now exploiting.

"In traditional data communication, information is transferred by something being either on or off. That can be as basic as a flashing light, or radio waves, or signals sent down optical fibres.

"Observers are able to see that data is being transmitted, even if they cannot read the message because of it being encrypted in some way. 

"But with negative luminescence it is possible to create a hidden signal using a special device called a thermoradiative diode." 

The diode can switch output quickly between brighter and darker-than-usual states which creates a pattern that blends into the usual background ‘noise’ and is therefore invisible to anyone not aware that data is being sent.

The hidden information transmitted by such thermoradiative diodes can also be encrypted in traditional ways, adding yet another level of security.