While nanophotonic devices have been used for optical processing for some time, the aim of late has been to use light to actually throw switches to control electronic circuits. Hong X. Tang of Yale University wrote on the pages of Spectrum three years ago about his success in using the pressure of light to operate nanomechanical devices.
Now researchers at the University of Pennsylvania have developed what they claim is the first all-optical nanowire switch. The research, which was published in the journal Nature Nanotechnology (“All-optical active switching in individual semiconductor nanowires”), not only succeeded in fashioning a switch from cadmium sulfide nanowires, but also managed to combine the photonic switches into a logic gate.
The idea that cadmium sulfide nanowires could be used to make optical switches derived from the researchers previous research that demonstrated that these nanowires possessed extraordinary strong light-matter coupling.
With that previous work as inspiration, the researchers set off on their current research and started by cutting a gap into a nanowire. They then ran energy through one of the nanowire pieces until it started to emit laser light from one end of it and started to bridge the gap to the other piece of nanowire.
“Once we have the light in the second segment, we shine another light through the structure and turn off what is being transported through that wire,” says associate professor Ritesh Agarwal in the university press release covering the research. “That's what makes it a switch.”
Agarwal and his colleague in the research, graduate student Brian Piccione, opted to combine their new switches together to assemble a logic gate. “We used these optical switches to construct a NAND gate, which is a fundamental building block of modern computer processing,” says Piccione in the press release.
While Agarwal makes a fair assessment that this work at least indicates that the future could become “consumer photonics” as opposed to “consumer electronics”, I think it also fair to say that we may still be a long way off from that eventual future. Definitely a step in the right direction though.
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.