The Stack Archive

Data centre model replaces cables with infrared laser links

Thu 2 Feb 2017

Infrared lasers

Communication in the data centre could be significantly simplified in the near future thanks to a new proposition which sees infrared links replace the ‘jungle’ of fibre-optic cables between server racks.

Microsoft engineers at Penn State University, Stony Brook University and Carnegie Mellon have outlined a system where infrared free-space optics would succeed fibre-optic wires in the data centre, beaming data through thin air to receptors situated around the room and redirecting communications via mirrors as required.

“We use a free space optical link. It uses a very inexpensive lens, we get a very narrow infrared beam with zero interference and no limit to the number of connections with high throughput,” explained lead researcher Mohsen Kavehrad, presenting his findings at the Photonics West 2017 conference in San Francisco.

Otherwise known as a Firefly architecture, the study notes how infrared lasers and receivers are placed on top of data centre racks to transmit information. These laser modules are rapidly reconfigurable to connect to a new target on any rack. Kavehrad proposes minimal human interaction in the model in order to avoid disruption to the laser beams.

So far, the team has built one $20,000 prototype and proved that the system can reach a delivery rate of 10 gigabits per second.

EE EAST LAB-6In the demo, Kavehrad used lasers to generate an infrared signal at a wavelength of 1550 nanometres – a common wavelength used in fibre-optic cabling. The signal then underwent wavelength-division multiplexing (WDM) – a technique used to pack a greater number of signals, with multiple wavelengths, onto a single laser beam. Next, the electrical engineer sent the beam through an inexpensive lens.

At a range of around 15 metres, he set up another lens and several receivers. Kavehrad also added a series of tiny mirrors powered by MEMS, or microelectromechanical systems to direct the beams.

The research estimates that by 2020 data centres will use a total of 140 billion kilowatts of electricity every hour. Kavehrad believes that introducing infrared lasers could allow data centre managers to more easily reconfigure server racks to support energy-savings, including better cooling management.

“We need to avoid over-provisioning and supply sufficient capacity to do the interconnect with minimal switches. We would like to get rid of the fibre-optics altogether,” he added.


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