  This article discusses the basic system architecture for terahertz (THz)
wireless links with bandwidths of more than 50 GHz into optical networks. New
design principles and breakthrough technologies are required in order to
demonstrate Tbps data-rates at near zero-latency using the proposed system
concept. Specifically, we present the concept of designing the baseband signal
processing for both the optical and wireless link and using an end-to-end (E2E)
error correction approach for the combined link. We provide two possible
electro-optical baseband interface architectures, namely transparent
optical-link and digital-link architectures, which are currently under
investigation. THz wireless link requirements are given as well as the main
principles and research directions for the development of a new generation of
transceiver frontends, which will be capable of operating at ultra-high
spectral efficiency by employing higher-order modulation schemes. Moreover, we
discuss the need for developing a novel THz network information theory
framework, which will take into account the channel characteristics and the
nature of interference in the THz band. Finally, we highlight the role of
pencil-beamforming (PBF), which is required in order to overcome the
propagation losses, as well as the physical layer and medium access control
challenges.
