QCL-based THz Optical Wireless Communication Link

In order to target high data-rates (1Tbps) with low latency $(\lt 10$ ms), THz frequency range seems to be the proper choice, allowing a higher carrier frequency with respect radio frequency (RF) or millimeter wave (mmWave) ranges, conventionally used in broadcasting methods. Furthermore, THz free space optical communication (FSOC) links are particularly interesting in harsh and industrial environments due to the larger wavelength which make the communication resistant to scattering with respect to near-IR and visible frequency ranges. Despite the growing interest, THz wireless communication (TWC) compact and reliable solutions have been realized especially in the sub-THz band (0.3-0.6 THz), that can still benefit of electronic devices for both the source and the receiver. Up to now, TWC in the 2-5 THz band has been performed using quantum cascade lasers (QCLs) and quantum well infrared photodetectors (QWIPs) both requiring strong cryogenic cooling. Here we present the first cryogen-free realization of a Free Space Optical Communication (FSOC) link based on a 2.83 THz QCL, cooled by a transportable closed-cycle cryostat, and a Graphene-based field-effect transistor (GFET) as the room-temperature receiver.