In an effort to trade electronics for photonics, a Purdue University-led team has created a way for electronic chips to use multiple colors concurrently by streamlining the manufacturing process.
Electronic chips that sense changes in scattered color run into limitations if they use only one color at a time. Since individual hues carry their own frequency, systems can achieve a higher bandwidth for transmitting information if they use more variety.
If chips utilizes multiple colors, then several data channels would be deployed simultaneously. In addition to widening the bandwidth of current electronic devices, this would also help nanophotonics. This faster technology centers around units of light called photons, which is an improvement from relying on slower, heavier electrons to process data at the nanoscale.
According to Purdue, IBM and Intel have already stepped into the photonics arena, creating a supercomputer chip that mixes light’s higher bandwidths with conventional electronic systems.
Taking the research baton at full stride, the Purdue manufacturing process not only allows for simplification, but also helps with another problem in the electronic to photonic transition—light-producing lasers need a size reduction in order to fit on the chip.
“A laser typically is a monochromatic device, so it’s a challenge to make a laser tunable or polychromatic,” says Alexander Kildishev, Purdue associate professor of electrical and computer engineering. “Moreover, it’s a huge challenge to make an array of nanolasers produce several colors simultaneously on a chip.”
A vital part of lasers is known as the optical cavity, which is the part that needs to be scaled down. The Purdue team, along with researchers from Stanford University and the University of Maryland, were able to embed silver metasurfaces in nanocavities. The metasurfaces are essentially artificial materials that are thinner than light waves, thus the resulting lasers are ultrathin.
“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,” says Kildishev. “Our nanocavities would make on-a-chip lasers ultrathin and multicolor.”
The silver metasurfaces allow for another benefit—each color can fuction with a uniform thickness. Traditional systems need varying optical cavity thickness dependent upon the desired color.
“Instead of adjusting the optical cavity thickness for every single color, we adjust the widths of metasurface elements,” says Kildishev.
Moreover, the metasurface could potentially take the place of traditional lenses used in today’s electronic devices.
“What defines the thickness of any cell phone is actually a complex and rather thick stack of lenses,” Kildishev adds. “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.”
The paper, “Ultrathin and multicolour optical cavities with embedded metasurfaces,” was published in the July issue of Nature Communications.