Optical filter structures based on the self-imaging phenomenon

Filtering of optical signals at very high data rates can be achieved in various ways. During recent years, for example, ring resonators have been investigated for the purpose of implementing infinite impulse response (IIR) filters. Here, we consider the implementation of finite impulse response (FIR) filters based on interferometric devices using self-imaging. Widely known is the Talbot self-imaging effect which is also being used for the implementation of optical beamsplitters. We shall begin with the Talbot effect to explain the realization of optical FIR filters and then consider the more general case of Montgomery self-imaging. Modeling, design and experimental demonstration of the Montgomery interferometer as a filtering device is presented.