A research team at Penn State has developed a plasmonic switch that may help pave the way for the next generation of super-fast computers.
"If plasmonics are realized, the future will have circuits as small as the current electronic ones with a capacity a million times better," said Tony Jun Huang, James Henderson assistant professor of Engineering Science and Mechanics. "Plasmonics combines the speed and capacity of photonic -- light based -- circuits with the small size of electronic circuits." – Science Daily
The researches created the switch from switchable bistable rotaxanes. Rotaxanes are mechanically-interlocked molecules that consist of a dumbbell shape with a ring or rings encircling the shaft and are sometimes called molecular machines. The movement of the rings along the shaft is the basis of the plasmonic switch.
“Computers, in their simplest form, are machines that can say yes or no multiple times to transfer information. The motion of a molecule can serve the same purpose as the on off switch on a light.”
An article from Penn State explains how the research team developed the plasmonic switch:
The researchers attached their molecular machines to gold-coated nanodiscs fabricated on glass. The machines were attached with disulfide functional groups. The dumbbell shaped molecules have two areas of the shaft primed with two different chemicals. The ring is initially drawn to circle at one primed area. When the chemical there is oxidized, the ring is repelled and moves to the other primed area, flipping the switch. The process is reversible, so the ring returns to its original state to switch on again later. When the molecule moves, it changes the surface plasmon resonance in that tiny area of the metal where it is attached. This change in resonance is what would send the signal on the circuit. The plasmonic switch that Huang and his team developed is not yet part of a circuit.
Plasmonics, sometimes referred to as “light on a wire”, is an emerging area that uses metal nanostructures to transmit optical signals through minuscule nanoscale structures. It can be used to bridge the worlds of electronic and optical circuits to transmit electrons and light at the same time using the surface of a circuit. This overcomes the capacity and speed limitations of pure electronic circuits as well as the the large size restriction of pure optical circuits, which send information at the speed of light with bulky reflective interiors.
All-plasmonic chips have yet to be developed, but the switch is a step in the right direction. The technology has other applications such as biosensors, and in 2007, researchers have merged plasmonics with another emerging field called spintronics to give birth to “spinplasmonics”, an approach that can lead to ‘computers with extraordinary capacities.’