Proposed graphene nanospaser

We propose a novel nanospaser that operates in the mid-infrared region and utilizes a nanopatch of graphene as its plasmonic core and a quantum-well cascade as its gain medium. This design takes advantage of the low optical losses in graphene resulting from its high electron mobility. The proposed quantum cascade graphene spaser generates optical fields with unprecedentedly high nanolocalization, which is characteristic of graphene plasmons. This spaser will be an efficient nanosource of intense and coherent hot-spot fields in the mid-infrared spectral region with potential widespread applications in mid-infrared nanoscopy, nanospectroscopy, nanolithography, and optoelectronic information processing. Researchers in the USA have proposed a nanoscale device that could be capable of creating a localized, intense mid-infrared field. Vadym Apalkov and Mark Stockman from Georgia State University say that their ‘nanospaser’ would be useful for applications such as nanospectroscopy, nanolithography and nanoscopy. Their design consists of a nanopatch of graphene that supports plasmons atop a gain-providing stack of semiconductor quantum wells. The system of quantum wells is similar to that found at the heart of a quantum cascade laser. When driven electrically, the nanospaser should generate concentrated, coherent optical fields that localize near the surface of the graphene. Although optically excited spasers have already been reported, this device, if experimentally realized, would be the world’s first electrically pumped spaser.