Simple epoxy device can steer light through sharp turns

A simple epoxy plastic could be an important key to optical computing, thanks to research by engineers from the Universities of Texas at El Paso (UTEP and Central Florida (UCF). The engineers have used a form of 3D printing to make a microscopic plastic lattice which guides light through sharp turns, an important property for guiding laser light that encodes data through the labyrinthine routes that would be needed in superfast optical computing systems.

Metallic wires used to carry datas encoded in electrical signals into semiconductor devices in conventional computers are fast, but using light rather than electricity is potentially a thousand times faster. But guiding light is difficult. Conventional waveguides use optical fibres, but these work by refelecting light off the internal surface of the fibre so they can only carry light through gentle curves: try a shap curve and the light will not reflect and will leak out. ‘The name of the game is being able to control these light beams,’ explained Javier Pazos of UTEP, who worked with research leader Ray Rumpf. ‘And we were able to do just that, with unprecedented success.’

The team used a technique called multiphoton lithography, or direct laser writing, to create a microscopic honeycomb lattice out of a photosensitive epoxy resin, which sets when hit with laser light of a specific wavelength. This lattice can turn a laser through a right-angle without losing energy. ‘The fact that we can do this with a simple plastic — an epoxy — is a pretty big deal,’ said Pazos. ‘Normally, you’d need an exotic, unheard-of material to even attempt this.’

According to Rumpf, the technique can bend light through whatever angle is needed, simply by changing the geometry of the lattice. Rumpf’s  electrical and computer engineering lab was responsible for the theory behind the device and its design, while UCF carried out the fabrication and testing under Stephen Keubler, a chemist, as the teams explain in a paper in the journal Optics Express.

‘Direct laser writing has the potential to become a flexible means for manufacturing next-generation computer devices,’ said Kuebler.

The device is likely to first find use in high-performance supercomputers, Rumpf said, but could also be used in compact, laptop-sized devices in future generations of the technology.