Novel device may lead to faster, cheaper internet

Scientists have developed a new phototransistor device that provides a low-cost and low-power alternative to traditional radio-frequency wireless data links, and may result in faster and cheaper internet.
With a growing number of people connecting to the web everyday, internet cables are under the threat of a "bandwidth explosion."
Free-space optical (FSO) communication is a promising candidate to lighten the load, researchers said.
FSO uses visible or infrared light to wirelessly transmit data through open air as opposed to using cables, which have limited bandwidth.
The new technology provides a low-cost and low-power alternative to traditional radio-frequency wireless data links, researchers said.

"The current state-of-the-art in FSO communications is based around near-infrared sources and photodetectors," said Manijeh Razeghi from Northwestern University in the US.

"Unfortunately, using these wavelengths come with major problems," said Razeghi.
At high power, near-infrared wavelengths can damage the human eye, and they are hampered by atmospheric scattering and absorption.
Razeghi has bypassed this issue by using mid-wavelength infrared radiation, which can benignly and flawlessly transmit through fog, smoke and clouds.
Razeghi and her team have developed an extremely sensitive mid-wavelength infrared photodetector that has the potential to replace near-infrared FSO communications links in many applications.
Called a phototransistor, the novel device is a combination of an electronic transistor and optoelectronic photodiode.

"For the first time, we have demonstrated a phototransistor that is totally made of an artificial semiconductor," said Razeghi.
"This extremely sensitive device could be a game changer for FSO communication technology by providing low-cost, high-speed data links," she said.
The research was published in the journal Applied Physics Letters.