A team of Boston College researchers in the lab of Professor Michael J. Naughton, the Evelyn J. and Robert A. Ferris Professor of Physics, has developed the very first nanoscale wireless communication system capable of working at visible wavelengths. The team’s research, detailed in the latest edition of the journal Nature Scientific Reports, finds that using specialized optical circuitry to help mimic the properties of extremely small wavelengths can have remarkable applications for next-generation technologies.
The article, “Wireless Communication System via Nanoscale Plasmonic Antennas,” explains that it is common for obstacles to interfere with developing improvements for signal transmission across computer chips. One such obstacle is the size of the electromagnetic waves used to test the efficacy of communication signals.
Small waves that mimic visible, infrared, and terahertz sequences exhibit behaviors ideal for microchip development. But current wireless technologies use relatively large electromagnetic waves at microwave and radio frequencies that prevent further miniaturization.
In an attempt to circumvent these limitations, Professor Naughton’s team sought to expedite the collection of electromagnetic radiation and the transmission of information on computer chips using a nanoantenna.
"We have developed a device where plasmonic antennas communicate with each other with photons transmitting between them," asserted Professor Naughton in a press release. "This is done with high efficiency, with energy loss reduced by 50 percent between one antenna and the next, which is a significant enhancement over comparable architectures."
Previously, ensuring that the emission and collection of electromagnetic radiation was collated along a single path was immensely difficult. As a result, communication signals across chips diminished in strength.
However, using a nanoantenna allowed the researchers to focus the photons onto a single path with an exceptional degree of control, thereby facilitating a two-way transmission of information across a single line of photons.
"[This] system is implemented in an in-plane configuration, meaning it allows information transmission and recovery via SPs (surface plasmons) propagating in the same plane," Professor Naughton claims.
Professor Naughton’s team reports that the new device could speed the transmission of information by as much as 60 percent compared to previous wave-guiding techniques, and up to 50 percent faster than models that use nanowires for signal transmission.
Furthermore, one of the techniques that greatly improved the operational efficiency of the device was the inclusion of a gap of air between the waves and the metal surface of the computer chip.
Professor Naughton’s team created this gap by removing a small portion of the glass substrate on the chip, which mitigated the resistive pull of the substrate on the photons during the electromagnetic wave collection process. This method allowed the researchers to focus the transmission of photons onto a single stream of particles.
The communication device also performs a three-step conversion process that changes surface plasmons (the fluctuations in electron density that occur when particles hit a surface) to photons on transmission. The device then converts the new electromagnetic particle back to a surface plasmon as the receiver picks it up, consequently reducing energy loss by almost 50 percent.
Dr. Juan M. Merlo, a postdoctoral fellow at the Naughton Lab at Boston College and the initiator of the project, explained that the new communication device is a step in the right direction to develop technologies for more accurate and energy-efficient signal transmissions.
"Silicon-based optical technology has been around for years," Merlo said. "What we are doing is developing a tool to make silicon photonics faster and greatly enhance rates of communication."