Fibre-optic connections created using surface-emitting lasers

Using unique surface-emitting laser technology, researchers have created efficient fibre-optic connections with a speed of around 40 gigabits per second.

The technology could have direct and immediate applications for industries that have already started using this type of laser, such as large data centres run by Google, eBay and Amazon and some supercomputer manufacturers.

‘The market for this technology is gigantic,’ said project lead Prof Anders Larsson of Chalmers University of Technology in Sweden. ’In the huge data centres that handle the internet there are today more than 100 million surface-emitting lasers. That figure is expected to increase 100-fold.’

The team was able to increase the speed of a surface-emitting laser around four-fold using a strained multi-quantum active region and multiple oxide layers.

Unlike a conventional laser, the light from a surface laser is emitted from the surface of the laser chip like in a light-emitting diode (LED).

The lasers can be fabricated and tested on the wafer before it is cut into individual chips for assembly — in contrast with conventional lasers that work only after partition. The ability to test up to 100,000 lasers on a wafer reduces the cost of production to one-tenth compared with conventional lasers.

There are also gains to be made in terms of efficiency. Surface lasers require less power without losing speed. Larsson predicts that with their technology the power consumption of a complete optical link, for example, between circuits in a computer, will be no more than 100 femtojoules per bit.

‘The laser’s unique design makes it cheap to produce, while it transmits data at high rates with low power consumption,’ Larsson said.

This combination could trigger a large-scale transition from electrical cables, which can handle up to a few gigabits per second, to optical cables for computer-to-peripheral equipment, as a substitute for USB cables.

Indeed, last month Intel launched its Thunderbolt (formerly Light-Peak) technology for optically connecting peripheral devices to a computer, with Apple’s MacBook Pro being the only compatible device currently.

The research is funded by the Swedish Foundation for Strategic Research and by the European Union through the VISIT project. Industrial partners include IQE Europe (UK), VI Systems (Germany) and Intel (Ireland).