Novel antenna-coupled terahertz photodetector with graphene nanoelectrodes

Antenna-coupled photomixers, serving as emitters and receivers of terahertz (THz) radiation, are the central active components of coherent optoelectronic THz systems. Here, we focus on the continuous-wave modality, which finds ample use for spectroscopy, sensing, and ranging and plays a major role in upcoming ultrahigh-frequency telecommunication applications. We demonstrate with planar receivers based on low-temperature-grown GaAs that the use of interdigital graphene electrodes instead of metal fingers enhances the responsivity by more than one order of magnitude. The increase in responsivity leads to a strongly enlarged dynamic range and doubles the frequency range covered in the detection process. We show by simulations that these improvements are a consequence of the transparency of the finger electrodes for visible/near-infrared laser radiation, which also activates the area under the fingers for the mixing process, not only their edges as in conventional devices with metal electrodes. (c) 2023 Author(s).

Automated summary

Antenna-coupled photomixers are important components in coherent optoelectronic THz systems. By using interdigital graphene electrodes instead of metal fingers, the responsivity of planar receivers based on low-temperature-grown GaAs can be enhanced significantly, leading to an enlarged dynamic range and doubled frequency range in the detection process. These improvements are attributed to the transparency of the finger electrodes for visible/near-infrared laser radiation, which activates the area under the fingers for the mixing process.