Infrared lasers have been a staple of optical fiber communications for some time, both for local and long-haul communications. Now, it seems research is turning toward taking the fiber out of the equation by establishing direct infrared connectivity over the air.
Multiple projects are currently underway in the US and Europe aimed at devising point-to-point and point-to-multipoint solutions in the data center and other digital environments, such as the office or the factory floor, that could replace today’s wired and wireless infrastructure with a robust, scalable and highly secure alternative.
At Penn State University, electrical engineering professor Mohsen Kavehrad has outfitted his lab with a wireless infrared system that he says delivers data rates up to 10Gbit/s. The system utilizes lasers mounted on server racks that link to photoreceptors across the room using the same 1550nm wavelength that is common in fiber networks. Using the same setup, Kavehrad can transmit a 1GHz television signal to a standard cable multiplexer simultaneously with the data feed, indicating that the system can function as a full UC solution.
Meanwhile, a team at the Netherlands’ Eindhoven University of Technology is using wireless infrared technology to create a “Li-Fi” network that is said to maintain throughput over 40Gbit/s no matter how many devices are online. The system utilizes a series of antennas located throughout a room, which are fed by optical fiber linked to a series of “passive diffraction gratings” that act as prisms to transmit different wavelengths at different angles. And, since line-of-sight is required to maintain connectivity, it would be inherently more secure than standard 2.5 or 5GHz Wi-Fi.
According to Joanne Oh, a PhD researcher on the project, the system is easy to set up and maintain, since it has no moving parts and draws no power, although it is better at downloads than uploads. A key challenge was maintaining connectivity to mobile devices as they move about the room, which was solved with a tracking system for individual devices and a mechanism to switch service from one antenna to another should line-of-sight be lost. Each device is assigned a unique wavelength, which provides consistent bandwidth to each user and eliminates interference from nearby networks. In the 1500nm band, there is some 200THz to play with, and Oh says she is able to maintain throughput of more than 42Gbit/s over 2.5 meters compared to barely 17Mbit/s on 5G Wi-Fi.
Other approaches to Li-Fi involve remote controlled mirrors and even using existing LED lighting as a ready-made optical indoor network, says Network World’s Patrick Nelson. As well, some researchers are looking to use solar panels in place of mirrors, which have the advantage of supplying their own power as well as acting as receivers.
With all of these projects in various stages of development, it is unclear exactly how disruptive infrared or even wireless visible laser networks will be to established technologies like fiber optics and microwave. Improving download speeds is certainly welcome, but line-of-sight requirements all but rule out situations in which users roam over even relatively short distances or data systems are housed in multiple buildings.
Still, engineering challenges have greeted all the great developments of the past, so there is no reason to expect wireless laser technology will not evolve to meet existing and future challenges. And in the end it will rise or fall according to the age-old formula: efficacy minus cost times a good marketing strategy.