Nanophotonics and Quantum Dots

 Digital Manufacturing Report has a very interesting article on nanophotonics written by John Kirkley on November 22nd.   The article discusses Ubiquitous High Performance Computing (UHPC) and the challenges with power.

Below is a snippet:

According to the release, "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 very rapid rate of 10 billion bits per second.
The researchers say it is a major step forward in providing a practical ultrafast, low-power light source for on-chip data transmission." Their findings have been published in the most recent edition of the journal Nature Communications.

Earlier this year the Stanford researchers had come up with a nanoscale laser that was also very efficient and fast, but it only operated at temperatures below 150 degrees Kelvin – a trifle cool for your standard datacenter. However, the new laser-based system can operate at room temperature, making it a prime candidate for next generation computer chips. The researchers say the device is a major step forward in providing a practical, ultrafast, low-power light source for on-chip data transmission.

The new device is a miracle of engineering that employs the scientific discipline known as nanophotonics. The Stanford team has inserted "quantum dots," tiny flecks of material made of indium arsenide which, when pulsed with electricity, emit light. A photonic crystal surrounding the dots acts as a mirror that bounces the light into the center of the LED and forces it to resonate at a single frequency.

Of interest to exascale designers is the fact that tests of the device show it can transmit information 10X faster than conventional devices while consuming 1,000 times less energy.

According to the Stanford press release, "In tech-speak, the new LED device transmits data, on average, at 0.25 femto-joules per bit of data." By comparison, today's typical "low" power laser device requires about 500 femto-joules to transmit the same bit.

"Our device is some 2,000 times more energy efficient than best devices in use today," said Jelena Vuckovic, an associate professor of electrical engineering at Stanford and the lead on the project.