Facebook touts that it has found a way to use laser detectors for new high-speed data communications systems, giving it independence from spectrum or licenses.
Facebook's Connectivity Lab showcased the technology on Tuesday, July 19, in a scientific journal. One of the purposes of Connectivity Lab is to find technology that puts high-speed internet in the hands of those who are out of reach from standard networks.
The most common way to offer internet signal is by using wireless systems, as the method is less costly than deploying miles of cables to less urban communities. However, standard wireless comes packed with two caveats: it has a relatively low speed cap and it requires government-approved radio spectrum.
Engineers tried to overpass these limitations and looked into how data could be sent from point A to point B via lasers. The big advantage behind such a system is that it works autonomously from spectrum or legislative permission, and an array of systems are able to function in the same general area without interference.
Keep in mind that sending high-speed signals via lasers is anything but simple.
First off, there is an inverse proportion between the size of the photodiodes that receive the signal and the speed of the signal. The quicker the signal, the tinier the diodes need to be. For high speed, photodiodes should be a few times smaller than a grain of rice.
Secondly, laser beams tend to spread out over long distances, which means that by the time they reach the destination (the detector) they need to be focused. This basically means the aperture of the system is quite small, meaning that for it to work you need a complex pointing and aiming system.
Thirdly, this is hard to achieve at low speeds, and making it run smooth at high speeds is a great feat of engineering.
Connectivity Lab says it managed to craft a detector that can operate at high speeds, although it is quite large.
Facebook's laser detector measures 126 square cm (19.53 square in). It is made out of plastic optical fibers that were "doped" to take in blue light. The fibers are positioned such that they form a flat area that works as the detector. The fibers exhibit luminescence, causing the blue light to be reemitted as green light as it travels down the fibers. At the opposing end, the fibers bundle together before meeting with a photodiode.
The technology is described at length in the Optica journal.
Facebook touts that the invention could be useful for both outdoor and indoor applications.
Outdoors, the technology might provide low-cost communication links for distances of 0.6 mile or more. Indoors, the laser-based signal could send high-definition video to mobile devices.
Connectivity Lab says it reached speeds of 2.1 Gbps while testing the new detector. One way to further increase the speed would be the use of infrared-sensitive materials. Voices familiar with the matter point out that tapping into wavelengths invisible to the human eye is one sure way to boost the speed.
Facebook CEO Mark Zuckerberg hinted last year that Connectivity Lab is working on a way to put lasers to work for offering an alternative to Wi-Fi, so it is good to see the efforts come to fruition.
