Graphene Quantum Optoelectronics

In addition to graphene’s exotic electronic behavior, graphene’s optical and optoelectronic properties, resulting from the low dimensionality and unique conical band structure, have also generated much excitement. Graphene’s optical absorption is nearly constant (2%) across the visible and infrared (IR) spectrum and is determined purely by fundamental physical constants. Amazingly, BLG can easily be resolved from SLG using only a standard optical microscope, since BLGs absorption is double that of SLG. At low photon energies (IR wavelengths), optical excitations can couple directly to collective surface plasmon states that propagate at the interface between metals and dielectric materials and should differ substantially for SLG, GNRs and BLG. In addition, graphene’s thermal conductivity is exceptionally high, which allows it to resist damage at very high optical powers, and even behave as a saturable absorber for ultrafast laser applications. Combining the absorption and thermal transport properties with the exotic electronic excitations expected in BLG and GNRs suggests that this atomically thin membrane may be a vital nanotechnology for photonic and optoelectronic applications.

The experiments take advantage of ultra-high quality graphene devices to probe the physics and applications of seamlessly integrated band gap engineered electronic and optoelectronic devices. By incorporating scanning laser excitation, optoelectronic measurements will investigate the optically induced photocurrent at ultrafast time scales and explore the relationship between optoelectronic and electronic behavior, particularly for applications at high speeds and highly efficient energy conversion. Beyond optoelectronics, we will investigate fundamentally different functionalities in graphene-based plasmonic device structures and probe the physics of propagating surface plasmons expected in this material.