“Mohsen Kavehrad, an electrical engineer at Pennsylvania State University in University Park and his team have been working on an optical transmission system that is capable of high data-transmission rates. One problem with using light is that you normally need a direct line of sight between transmitter and receiver. Kavehrad's system gets round this by using a high-power laser diode to generate pulses of infrared light, which can be bounced off the ceiling. The reflected light is captured and refocused at the receiver, where a special semiconductor known as an avalanche photo diode turns light into a digital signal. The team have been able to transmit data at 1 Gbps, and think it can go even faster. They presented the work at the SPIE Phonotics West Conference in San Francisco last month.
Adding reflectors and more sensors could allow light to be bounced into separate rooms, claims Kavehrad, getting round one of the problems with 60 GHz radio systems. Optical systems should also be "greener" as their components generally use less energy than those transmitting radio waves. It would not interfere with other electronic systems, making it suitable for hospitals and aircraft, where Wi-Fi use has traditionally been restricted, he adds.”