Each color of light has its own specific frequency and wavelength. The more the frequency, the higher the bandwidth for transmitting information. Since many electronic chips use only one color of light at a time, it limits technologies that are based on sensing the changes in scattered color, like detecting viruses in blood samples, or developing airplane images of say, forest vegetation.
Employing multiple colors of light at once would help manage multiple channels of information simultaneously, which will help broaden the bandwidth the bandwisth of not only the electronics we have today, but also of the faster “nanophotonics” of the future. These “nanophotonics” will be based on photons rather than on slow and heavy electrons to handle the information with nanoscale devices.
IBM and Intel have already made supercomputer chips which combine the higher bandwidth of light with traditional electronic structures. Amidst this search for solutions of replacing electronics with nanophotonics eventually, a new study, led by a research team from Purdue University, has proposed a manufacturing process that makes utilizing multiple colors at the same time on an electronic chip possible, instead of just sticking to a single color.
The research team also addressed the issue of transition from electronics to nanophotonics,which is posed by the fact that the lasers which produce light will need to be smaller top fit on the electronic chip. “A laser typically is a monochromatic device, so it’s a challenge to make a laser tunable or polychromatic,” said Alexander Kildishev, Associate Professor of Electrical and Computer Engineering at Purdue University. “Moreover, it’s a huge challenge to make an array of nanolasers produce several colors simultaneously on a chip.”
To make this possible, it is required that the “optical cavity”- a major component of lasers- is downsized. Researchers from Purdue University, Stanford University and the University of Maryland, have, for the first time ever, embedded silver metasurfaces in the nanocavities. These “metasurfaces” are artificial materials which are significantly thinner than light waves.
“Optical cavities trap light in a laser between two mirrors. As photons bounce between the mirrors, the amount of light increases to make laser beams possible,” Kildishev added. “Our nanocavities would make on-a-chip lasers ultrathin and multicolor.” The study was published recently in the journal Nature Communications.
“Instead of adjusting the optical cavity thickness for every single color, we adjust the widths of metasurface elements,” Kildishev said. “What defines the thickness of any cell phone is actually a complex and rather thick stack of lenses.If we can just use a thin optical metasurface to focus light and produce images, then we wouldn’t need these lenses, or we could use a thinner stack.”