Researchers have developed a to deliver data through free space by eliminating the need of fiber optic cable for light.
Using light as a medium of communication can seem to be faster and a very advanced tech. But as we are using light, what if what about the medium of transmission? The present state-of-the-art technology uses fiber cables as their medium of transmission, but what if this information carrying light could be transmitted as normal light? What advancement could lead to that?
New signal-processing algorithms have been shown to mitigate the impact of turbulence in free-space optical experiments, potentially bringing “free space” internet a step closer to reality. A team of researchers, from Aston University’s Aston Institute of Photonic Technologies and Glasgow University, used commercially available photonic lanterns, a commercial transponder, and a spatial light modulator to emulate turbulence. By applying a successive interference cancelation digital signal processing algorithm, they achieved record results.
The researchers simultaneously transmitted multiple data signals using different spatially shaped beams of light using a so-called photonic lantern. Turbulence changes the shape of the beams, often losing the signal if only a single simple shape is transmitted and detected, but by detecting light with these shapes using a second lantern, more of the light is collected at the receiver, and the original data can be unscrambled. This can greatly reduce the impact of the atmosphere on the quality of the data received, in a technique known as Multiple-input multiple-output (MIMO) digital signal processing.
According to professor Andrew Ellis at Aston University said, “Using a single beam, when a single beam was transmitted, turbulence similar to a hot sunny day destroyed the signal 50% of the time. By transmitting multiple beams of different shapes through the same telescopes and detecting the different shapes, not only did we increase the availability to more than 99%, we increased the capacity to more than 500 Gbit/s, or more than 500 ultra-fast Pure-Fiber broadband links.”
This project aims to provide the internet performance of a Pure-Fiber connection without the need to install cables. It uses a free space optical communication system that can link to remote sites using a wireless optical line of site signal to link to nearby fiber sources in more affluent suburbs.
Reference : Yiming Li et al, Enhanced Atmospheric Turbulence Resiliency With Successive Interference Cancellation DSP in Mode Division Multiplexing Free-Space Optical Links, Journal of Lightwave Technology (2022). DOI: 10.1109/JLT.2022.3209092