A Thresholder for all-optical Digitising Radio-over-Fibre transceivers

This paper describes an optical Thresholder (o-Thresholder) intended to be part of a transmitter module for future all-optical Digitising Radio-over-Fibre (o-DRoF) transceivers. The proposed device is based on an Attenuation-Imbalanced Semiconductor Laser Amplifier Loop Mirror (AI-SLALOM) in self-switching regime, using the nonlinearities of a semiconductor optical amplifier. Simulations of the proposed AI-SLALOM based o-Thresholder have shown promising results in comparison with the use of standard optical fibre and highly nonlinear fibre only. The newly proposed device is rather compact, optically integrable and requires much less input optical power than conventional devices (by several orders of magnitude). It provides enhanced optical RZ bits at 1550 nm wavelength window, 1.25 GHz repetition rate and 80 ps time-width.