SUMMARYContinued progress in both civil and military radio-frequency (RF) digital avionics applications is overstressing the capabilities and reliability of existing RF communication networks based on coaxial cables on board modern aircrafts. Future avionics systems will require high-bandwidth on-board communication links that are lightweight, immune to electromagnetic interference, and highly reliable. Fibre-optic networks can meet all these challenges in a cost-effective manner. Recently, on-board fibreoptic communication systems, where a fibre-optic network acts like a local area network (LAN) for digital data communications, have become a topic of extensive research and development. However, modern digital avionics systems require a system capable of transporting microwave and millimeter-wave RF signals that carry digital data on board an aircraft. Such optical networks transporting RF signals are completely different from the digital fibre-optic communication systems.Recent advances in optoelectronics technology, including linear optoelectronic devices and wavelength division multiplexing (WDM), have opened a number of possibilities for designing on-board fibre-optic networks, including all-optical networks for digital avionics RF signal communication. The objective of this paper is to present a number of optical network architectures for transmitting RF signals carrying digital data in an aircraft.In this paper, we investigate a number of different approaches, including all optical architectures, for building an optical network using fibre-optic transmission of on-board VHF and UHF RF signals. The relative merits and demerits of the network architectures are discussed, and the suitability of the architectures for particular applications is presented.