Researchers from the ICFO, in collaboration with CIC nanoGUNE, Columbia University and the National Institute for Materials Science in Japan, have been able to fabricate an all-graphene mid-infrared plasmon detector operating at room temperature, where a single graphene sheet serves simultaneously as the plasmonic generation medium and detector.
The team used an experimental design with two local gatesâ€”a split metal sheet located underneath the grapheneâ€”to fully tune the thermoelectric and plasmonic behavior of the graphene. In contrast to the conventional back gating through a thick SiO2 layer, the separate local gates not only induce free carriers in the graphene to act as a plasmonic channel, but also create a thermoelectric detector for the plasmons. The resulting device converts the conveniently available natural decay product of the plasmon, electronic heat, directly into a voltage through the thermoelectric effect.
The results of this paper may open a new pathway to graphene 'plasmo-electronics´, which would allow to perform mid-infrared opto-electronics at very small length scales. The team will further attempt to create a fully integrated system in which all three parts - source, channel, and receiver, are made of graphene, enabling a new ´all-carbon optics´ technology.