Graphene, that atom-thick sheet of carbon, is a wonder-material many hope will one day be used in electronics thanks to its almost unbelievable conductive properties. Unfortunately, in some ways it conducts too well as the material it would likely replace, silicon, is a semiconductor. Before graphene electronics could really be made, an effective and easy way to make it into a semiconductor has to be found and researchers at Rice University have an intriguing solution.
The properties of silicon are not always what one wants, but by introducing impurities, or doping the silicon, the desire properties are created. Researchers have been experimenting with doping graphene but the Rice researchers have changed the game some by making its dopants plasmonic antennas. A plasmon is a photon coupled with an electron that will travel along a conductor, including graphene, just like an electron. When light of the proper frequency shines on the plasmonic antennas, they can produce hot electrons that actually disrupt the graphene and dope it in certain spots to make it a semiconductor.
Using this method, one could shine a light on a sheet of graphene and change the circuit pattern on it. By carefully tuning the responses of the plasmonic antennas, different frequencies of light could have varying effects on the graphene as well.