For years the prospects of photonic circuits—those that use photons instead of the electrons—were mired in a lack-of-space problem: A photonic system couldn’t get any smaller than a wavelength of light, about 1000 nanometers for infrared, while some dimensions of today’s transistors are one one-hundedth that size.
Enter plasmonics in which devices exploit the oscillating waves of electrons that are generated when photons hit a metal surface. Plasmonic-based approaches confine the size of the wavelength and makes it possible to fabricate smaller devices. But plasmonics for photonic circuits has some drawbacks too, namely surface-of-the-sun type heat.
Now researchers at Moscow Institute of Physics and Technology's (MIPT) Laboratory of Nanooptics and Plasmonics have found a solution to the problem of overheating of active plasmonic components using industry-standard heatsinks. If this solution proves successful, the prospects for photonic circuits will have brightened significantly.
In research described in a paper in ACS Photonics, the Moscow scientists have demonstrated in simulations that using a high-performance thermal interface can significantly reduce the amount of heat generated in photonic circuits. Thermal interfaces are essentially layers of thermally conductive materials placed between the chip and the heat sink. For instance, thermal grease is a popular type of thermal interface used in today’s electronic circuits to extract heat.
The two MIPT researchers, Dmitry Fedyanin and Andrey Vyshnevyy, who led this research and offer an explanation of their work in the video below, found that a photonic chip employing plasmonic waveguides would experience increases in temperatures of several hundreds of degrees Celsius. But in their simulations, the rsearchers found that multi-layered thermal interfaces of nano- and micrometer thickness combined with a simple cooling systems can reduce the temperature down to about 10 degrees Celsius. And this was accomplished with the aide of a simple fan cooling system.
While this work is just simulations at present, the researchers believe that if physical experiments work it could lead to the use of such interfaces in high-performance optoelectronic microprocessors in supercomputers, compact electronics, and other applications.
Editor’s Note: Due to a mix up between two press releases, it was stated that metamaterials constituted the thermal interface. This was incorrect. The cooling system using high-performance thermal interfaces was based on a conventional heat sink system to cool the device. Changes have been made to the original piece to correct this mistake. (Both works were based on studies at the Moscow Institute of Physics and Technology (MIPT): In one metamaterials were used in photonic circuits, and in another the use of high-performance thermal interfaces were developed to reduce temperatures in photonic circuits.)
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.