Nanowires are a step towards photonic chip

Australian researchers have engineered one of the world’s smallest ever nanowires for the next generation of telecommunication technology, bringing them one step closer to the holy grail of optics – the creation of a ‘photonic chip’ which would lead to a faster, more sustainable internet.

This is a significant step towards the realisation of the photonic chip.

Nano Letters – Generation of λ/12 Nanowires in Chalcogenide Glasses

Nanowires have been widely studied and have gained a lot of interest in the past decade. Because of their high refractive index and high nonlinearity, chalcogenide glasses (ChGs) are a good candidate for the fabrication of photonic nanowires as such nanowaveguides provide the maximal confinement of light, enabling large enhancement of nonlinear interactions and group-velocity dispersion engineering. Here we report on the generation of λ/12 (68 nm) nanowires based on the theoretical and experimental study of the influence of the laser repetition rate on the direct laser fabrication in ChGs (λ = 800 nm). Through a numerical model of cumulative heating, the optimum conditions for high-resolution fabrication in As2S3 are found. Nanowires with dimensions down to λ/12 are for the first time successfully fabricated in ChGs. We show that the generated nanowires can be stacked to form a three-dimensional woodpile photonic crystal with a pronounced stop gap

The realisation of a photonic chip will rely on a range of factors, including the fabrication of extremely small materials and the researchers’ ability to harness a unique optical property known as the ‘non-linear effect’.

This is where the Australian team’s tiny new nanowires come into play.

“In order to make the chip small, every component needs to be extremely small,” Nicoletti said. “So we always try to push it that bit further to make our nanostructures as tiny as possible.”

Up until now, researchers have only been able to make nanowires of this size in polymers, which don’t have the same unique characteristics as chalcogenide glass.

Chalcogenide exhibits non-linearity, which means its optical density changes according to the applied light intensity.

“If you pump high density light into an optic fibre made of non-linear material, you can actually change its properties, and therefore change the way other light moves along it,” Nicoletti said

It is this combination of tiny materials and non-linearity, which has brought the researchers one step closer to their ultimate goal.

According to Professor Min Gu, who is Director of Swinburne’s Centre for Micro-Photonics and leading the Swinburne arm of CUDOS, the group’s success will not only create a much faster internet, it will also lead to a more sustainable one.

“Not many people realise this, but the internet is a major energy consumer. It’s projected that in the next decade it will count for half of the world’s energy use,” he said. “So making it more efficient will make a huge difference to our carbon footprint.”

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