Cryogen-free, QCL-based Free Space THz Communication link

Wireless networks are evolving to respond to the growing request for higher data rates (several hundreds of Gbps to several Tbps), which are expected to be the design goals of the next generation 6G communications systems. In this framework, communication links could benefit from the higher carrier frequency intrinsically available in the THz band. At present, only the 0.3-0.6 THz region has been explored and various wireless communication links are reported in this sub-THz spectral region, still accessible by the electronics-based devices [1,2]. The recent growth of THz photonics, in particular the development of Quantum Cascade Lasers (QCLs) as high-power THz sources, allows Free Space Optical Communication (FSOC) in the 2-5 THz band. However, all the setups reported up to now require strong cryogenic cooling, for both QCL sources and quantum well photodetectors stages, in the order of 10 K [3,4].