A team at Stanford’s School of Engineering has demonstrated an ultrafast nanoscale light-emitting diode (LED) that is orders of magnitude lower in power consumption than today’s laser-based systems and is able to transmit data at the rapid rate of 10 billion bits per second. Researchers say this is a major step forward in providing a practical ultrafast, low-power light source for on-chip data transmission.
The LED in question is a “single-mode LED,” a special type of diode that emits light more or less at a single wavelength, similarly to a laser. “Our nanophotonic, single-mode LED can perform all the same tasks as lasers, but at much lower power,” said Gary Shambat, a doctoral candidate in electrical engineering.
Nanophotonics is key to the technology. In the heart of their device, the engineers have inserted little islands of the light-emitting material indium arsenide, which, when pulsed with electricity, produce light. These “quantum dots” are surrounded by photonic crystal – an array of tiny holes etched in a semiconductor. The photonic crystal serves as a mirror that bounces the light toward the center of the device, confining it inside the LED and forcing it to resonate at a single frequency.
The technology combines light transmission and modulation functions into one device, reducing energy consumption. The LED device transmits data, on average, at 0.25 femto-joules per bit of data. By comparison, today’s typical “low” power laser devices require about 500 femto-joules to transmit the same bit – making this device some 2,000 times more energy-efficient than the best devices in use today, said researchers.
Also: A laser communications system uses deformable mirrors to offer a data transmission boost to broadcasters.
