Breakthrough in photonics could allow for faster and faster electronics

Oct 01, 2013

(Phys.org) —A pair of breakthroughs in the field of silicon photonics by researchers at the University of Colorado Boulder, the Massachusetts Institute of Technology and Micron Technology Inc. could allow for the trajectory of exponential improvement in microprocessors that began nearly half a century ago—known as Moore's Law—to continue well into the future, allowing for increasingly faster electronics, from supercomputers to laptops to smartphones.

The research team, led by CU-Boulder researcher Milos Popovic, an assistant professor of electrical, computer and energy engineering, developed a new technique that allows microprocessors to use light, instead of electrical wires, to communicate with transistors on a single chip, a system that could lead to extremely energy-efficient computing and a continued skyrocketing of computing speed into the future.

Popovic and his colleagues created two different optical modulators—structures that detect electrical signals and translate them into optical waves—that can be fabricated within the same processes already used in industry to create today's state-of-the-art electronic microprocessors. The modulators are described in a recent issue of the journal Optics Letters.

First laid out in 1965, Moore's Law predicted that the size of the transistors used in microprocessors could be shrunk by half about every two years for the same production cost, allowing twice as many transistors to be placed on the same-sized silicon chip. The net effect would be a doubling of computing speed every couple of years.

The projection has held true until relatively recently. While transistors continue to get smaller, halving their size today no longer leads to a doubling of computing speed. That's because the limiting factor in microelectronics is now the power that's needed to keep the microprocessors running. The vast amount of electricity required to flip on and off tiny, densely packed transistors causes excessive heat buildup.

"The will keep shrinking and they'll be able to continue giving you more and more computing performance," Popovic said. "But in order to be able to actually take advantage of that you need to enable energy-efficient communication links."

Breakthrough in photonics could allow for faster and faster electronics

Microelectronics also are limited by the fact that placing electrical wires that carry data too closely together can result in "cross talk" between the wires.

In the last half-dozen years, microprocessor manufacturers, such as Intel, have been able to continue increasing computing speed by packing more than one microprocessor into a single chip to create multiple "cores." But that technique is limited by the amount of communication that then becomes necessary between the microprocessors, which also requires hefty electricity consumption.

Using light waves instead of electrical wires for microprocessor communication functions could eliminate the limitations now faced by conventional microprocessors and extend Moore's Law into the future, Popovic said.

Optical communication circuits, known as photonics, have two main advantages over communication that relies on conventional wires: Using light has the potential to be brutally energy efficient, and a single fiber-optic strand can carry a thousand different wavelengths of light at the same time, allowing for multiple communications to be carried simultaneously in a small space and eliminating cross talk.

Optical communication is already the foundation of the Internet and the majority of phone lines. But to make an economically viable option for microprocessors, the photonics technology has to be fabricated in the same foundries that are being used to create the microprocessors. Photonics have to be integrated side-by-side with the electronics in order to get buy-in from the microprocessor industry, Popovic said.

"In order to convince the semiconductor industry to incorporate photonics into microelectronics you need to make it so that the billions of dollars of existing infrastructure does not need to be wiped out and redone," Popovic said.

Last year, Popovic collaborated with scientists at MIT to show, for the first time, that such integration is possible. "We are building photonics inside the exact same process that they build microelectronics in," Popovic said. "We use this fabrication process and instead of making just electrical circuits, we make photonics next to the electrical circuits so they can talk to each other."

In two papers published last month in Optics Letters with CU-Boulder postdoctoral researcher Jeffrey Shainline as lead author, the research team refined their original photonic-electronic chip further, detailing how the crucial , which encodes data on streams of , could be improved to become more energy efficient. That optical modulator is compatible with a manufacturing process—known as Silicon-on-Insulator Complementary Metal-Oxide-Semiconductor, or SOI CMOS—used to create state-of-the-art multicore microprocessors such as the IBM Power7 and Cell, which is used in the Sony PlayStation 3.

The researchers also detailed a second type of optical modulator that could be used in a different chip-manufacturing process, called bulk CMOS, which is used to make memory chips and the majority of the world's high-end .

Vladimir Stojanovic, who leads one of the MIT teams collaborating on the project and who is the lead principal investigator for the overall research program, said the group's work on optical modulators is a significant step forward.

"On top of the energy-efficiency and bandwidth-density advantages of silicon-photonics over electrical wires, integrated into CMOS processes with no process changes provides enormous cost-benefits and advantage over traditional photonic systems," Stojanovic said.

Explore further: Yellowstone's thermal springs—their colors unveiled

Related Stories

Graphene photodetector integrated into computer chip

Sep 16, 2013

The novel material graphene and its technological applications are studied at the Vienna University of Technology. Now scientists succeeded in combining graphene light detectors with semiconductor chips.

Photonics: Graphene boosts on-chip light detectors

Sep 16, 2013

The fabrication of high-performance light detectors—important for computers and mobile devices—using graphene integrated onto a chip is reported in three independent studies published online this week ...

Microchips' optical future

Feb 15, 2012

Computer chips are one area where the United States still enjoys a significant manufacturing lead over the rest of the world. In 2011, five of the top 10 chipmakers by revenue were U.S. companies, and Intel, ...

Recommended for you

Finding faster-than-light particles by weighing them

3 hours ago

In a new paper accepted by the journal Astroparticle Physics, Robert Ehrlich, a recently retired physicist from George Mason University, claims that the neutrino is very likely a tachyon or faster-than-light par ...

Controlling core switching in Pac-man disks

Dec 24, 2014

Magnetic vortices in thin films can encode information in the perpendicular magnetization pointing up or down relative to the vortex core. These binary states could be useful for non-volatile data storage ...

World's most complex crystal simulated

Dec 24, 2014

The most complicated crystal structure ever produced in a computer simulation has been achieved by researchers at the University of Michigan. They say the findings help demonstrate how complexity can emerge ...

Atoms queue up for quantum computer networks

Dec 24, 2014

In order to develop future quantum computer networks, it is necessary to hold a known number of atoms and read them without them disappearing. To do this, researchers from the Niels Bohr Institute have developed ...

New video supports radiation dosimetry audits

Dec 23, 2014

The National Physical Laboratory (NPL), working with the National Radiotherapy Trials Quality Assurance Group, has produced a video guide to support physicists participating in radiation dosimetry audits.

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

srikkanth_kn
1 / 5 (2) Oct 01, 2013
In order to convince the semiconductor industry to incorporate photonics into microelectronics you need to make it so that the billions of dollars of existing infrastructure does not need to be wiped out and redone
.

Photonics is still in early stages. Since it does promise exponential processing speed and energy efficiency, existing infra will surely make room (or make way) for it. Why looking for marketing pitch already ?
Eikka
2.3 / 5 (3) Oct 01, 2013
First laid out in 1965, Moore's Law predicted that the size of the transistors used in microprocessors could be shrunk by half about every two years for the same production cost, allowing twice as many transistors to be placed on the same-sized silicon chip. The net effect would be a doubling of computing speed every couple of years.


Misquotation of Moore's law: check.

Moore's law didn't predict - it merely observed.

The projection has held true until relatively recently.


It actually broke down completely in the 90's, but then Intel's CEO re-defined the law to include transistor speed into the same mix to keep it in line with Intel's development roadmaps.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.