All-optical microwave frequency filters

This paper introduces the field of all-optical signal processing at microwave frequencies, in which optical fibre networks are used to realise signal processing functions. The fundamental principles are explained, and the components of these structures described. An analysis of basic film structures, which can be used as building blocks for more complicated structures, is included with supporting measurements. Finally a new algorithm for the synthesis of window responses using an all-passive network is explained and demonstrated.