Exploiting hot-electron photoconductivity in graphene for terahertz photomixer detection

The ultrafast periodic heating and cooling of electrons in graphene, driven by a two-color optical beat signal, provides an alternative mechanism to realize terahertz (THz) photomixers, owing to the large bolometric photoconductivity. This allows operation over a broad range of optical wavelengths without the need for specialized epitaxial sample growth used in conventional semiconductor (SC) devices based on interband photoconductivity. We have recently demonstrated coherent, continuous-wave THz detection up to 0.7 THz in multi-layer graphene devices with telecom-wavelength optical lasers. In the case of detection, the bias-free operation allows operation without any dark current. Here we further investigate the physical origin of the effect and experimental performance using simulations of the hot-electron dynamics, and discuss potential routes to reach the sensitivity of state-of-the-art SC photomixers.