Forget fibre optics – the quickest way to send large amounts of data over long distances is through the air with a laser. In principle, laser beams bounced off an orbiting satellite could send 100 gigabytes of data per second and reach anywhere on Earth – or the solar system. Although all previous attempts to create free-space optical communication systems have encoded information by varying the intensity of the laser – amplitude modulation (AM) – scientists at Stevens Institute of Technology in New Jersey recently figured out how to send data by varying the frequency of the laser. This frequency-modulating (FM) signal is less sensitive to disruptions from fog, dust and rain. The researchers are now seeking ways to increase data speed. (See “Tangling with telecoms”, July 2011).
