A device that looks like a tiny washboard may clean the clocks of current commercial products used to manipulate infrared light.
New research by the Rice University lab of Qianfan Xu has produced a micron-scale spatial light modulator (SLM) like those used in sensing and imaging devices, but with the potential to run orders of magnitude faster. Unlike other devices in two-dimensional semiconducting chips, the Rice chips work in three-dimensional "free space."
Xu and his Rice colleagues detailed their antenna-on-a-chip for light modulation this week in Nature's open-access, online journal Scientific Reports.
The manipulation of light has become central to the information economy. Think about light-reflecting compact discs and their video variants and all the ways lasers are used, from sensing to security to surgery. Light carries data through optical fibers for telecommunications and signals on the molecular scale as photonics techniques improve. Light-emitting diodes power television displays (for viewers clutching infrared remotes) and are beginning to replace the inefficient light bulbs in homes.
But in the computer space, light has been bound and gagged by two-dimensional circuitry, tied to waveguides that move it from here to there, Xu said. He and his colleagues point out in the new paper that 2-D systems fail to take advantage of "the massive multiplexing capability of optics" made possible by the fact that "multiple light beams can propagate in the same space without affecting each other."
The researchers see great potential for free-space SLMs in imaging, display, holographic, measurement and remote sensing applications.
Simply put, the Rice team's microscopic SLM chips are nanoscale ribs of crystalline silicon that form a cavity sitting between positively and negatively doped silicon slabs connected to metallic electrodes. The positions of the ribs are subject to nanometer-scale "perturbations" and tune the resonating cavity to couple with incident light outside. That coupling pulls incident light into the cavity. Only infrared light passes through silicon, but once captured by the SLM, it can be manipulated as it passes through the chip to the other side. The electric field between the electrodes turns the transmission on and off at very high speeds.
Individual SLMs are analogous to pixels, and Xu, an assistant professor of electrical and computer engineering, sees the possibility of manufacturing chips that contain millions of them.
In conventional integrated photonics, "You have an array of pixels and you can change the transmission of each pixel at a very high speed," he said. "When you put that in the path of an optical beam, you can change either the intensity or the phase of the light that comes out the other side.
"LED screens are spatial light modulators; so are micromirror arrays in projectors, in which the mirrors rotate," he said. "Each pixel changes the intensity of light, and you see an image. So an SLM is one of the basic elements of optical systems, but their switching speed is limited; some can get down to microseconds, which is okay for displays and projection.
"But if you really want to do information processing, if you want to put data on each pixel, then that speed is not good enough." Xu said the Rice team's device "can potentially modulate a signal at more than 10 gigabits per second.
"What we show here is very different from what people have been doing," he said. "With this device, we can make very large arrays with high yield. Our device is based on silicon and can be fabricated in a commercial CMOS factory, and it can run at very high speed. We think this can basically scale up the capability of optical information processing systems by an order of several magnitudes."
As an example, he suggested the device could give the single-pixel camera in development at Rice – which at the beginning took eight hours to process an image – the ability to handle real-time video.
"Or you could have an array of a million pixels, and essentially have a million channels of data throughput in your system, with all this signal processing in parallel," he said. "If each pixel only runs at kilohertz speeds, you don't get much of an advantage compared with microelectronic systems. But if each pixel is working at the gigahertz level, it's a different story."
Though Xu's antennas would not be suitable for general computing, he said, they could be capable of optical processing tasks that are comparable in power to supercomputers. "Optical information processing is not very hot," he admitted. "It's not fast-developing right now like plasmonics, nanophotonics, those areas. But I hope our device can put some excitement back into that field."
Rice University: http://media.rice.edu
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
Scientists have separated a particle from one of its physical properties - proving a theory known as the "quantum Cheshire Cat".
A new material, combined with a cheap tracking system, could unleash the promise of concentrated solar power.A material with optical properties that change to help it capture more incoming sunlight could cut the cost of solar power in half, according to Glint Photonics, a startup recently funded by the Advanced Research Projects Agency for Energy (ARPA-E).
So much of the food we eat these days is encased in plastic. And behind it is a whole lot of research and innovation. We dive into some of the materials that keep food fresh and portable.
Researchers at MIT have created a ball with a customizable surface texture through the science of wrinkling.
A new way of turning vegetable waste directly into bioplastics could make such materials even more environmentally friendly
A 2-billion-year-old rock has revealed the first evidence of the isolated pockets where oxygen-breathing life may have evolved
A series of explosions set off by a team of scientists were expected to rattle Washington state's Mount St. Helens on Wednesday as researchers map the interior of the volcano, whose 1980 eruption was the deadliest in U.S. history.
Researchers say the right mix of erosion and stress creates Earth’s natural sandstone arches and columns
Michael Slezak goes deep under the outback to find a home for the southern hemisphere's first WIMP detector, which could confirm our best direct signal yet
Pick the right plastic off a refuse tip, then shred, melt and convert it into feedstock for 3D printers – it's a living for some of India's poorest people