Making light work of communications: the evolution of photonics
As early as the 1850s light beams were funneled through streams of water to create fantastically coloured fountains, a curiosity for the public. At that time a future of high-speed communications built upon this basic technology was beyond the comprehension of physicists.
That future is now. With the use of fibre-optic cables internet signals flash around the globe in milliseconds. Developed from traditional optics technology, photonics is the study and manipulation of the basic components of light: photons.
Professor Ben Eggleton, Director of the Centre for Ultra-high Bandwidth Devices for Optical Systems (CUDOS), is on a mission to revolutionise communication systems with the photonic chip. “Photonic chips process extraordinary amounts of data, making speed crucial. We are working on an all-optical switch to replace cumbersome electronic switches that dramatically slow data transmission. Signals from optic fibres are slowed when they reach copper based electrical switches: it takes time to convert the data-rich optical signals to an electrical format.” Eggleton’s all-optical signal processing overcomes this electronic speed hump and will vastly increase the speed of the internet.
To do this, Eggleton has turned the field of communications on its head, exploiting a common problem in fibre-optic communication: nonlinearities. A nonlinear material will undergo a transformation of its properties when exposed to intense light, distorting signal transmission and potentially corrupting information. Even when these distortions are minor, they become amplified when signals travel over long distances.
However processing of signals at the end of the fibres involves complex changes, such as amplification, and this is precisely where Eggleton has made use of the normally meddling influence of nonlinearity. “The key to CUDOS’ research is to investigate new materials that exhibit massive optical nonlinearities and use them for complex signal processing.”
Silica optical fibres used in standard communication chips are not ideal for making compact devices. Using chalcogenide glass, Eggleton and team create smaller chips hundreds of times stronger than silicon devices. “We’re creating materials with the greatest nonlinear optical capability ever demonstrated. Implanted in new devices they are the future of communications systems, allowing tunable optics and enabling the transfer of data at a faster rate.”
Even though the use of photonics is commonplace, researchers in the Faculty of Science are out to unleash photonics on a range of experimental technologies including those for telecommunications, biomedicine, astrophysics and the sensing power of security devices.
Eggleton has extended his work to microfluidics, a relatively new science that manipulates fluids in minute volumes. “Liquids add a layer of control to photonic devices, increasing our ability to fine tune their interactions with light. Photonic crystals are the backbone of this technology, increasing precision and providing the potential to be reversible,” explains Eggleton.
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