Very high Q-factor microwave photonic FIR filter based on a ultralong FBG cascade

Abstract

We report on a novel approach to the implementation of a photonic microwave filter that is based on 500 weak fiber Bragg gratings written in cascade while drawing a 5m-long fiber section. A very high quality factor (Q>1400) is experimentally demonstrated. To our knowledge this is the highest Q factor reported for a non infinite impulse response MWP filter and is over one order of magnitude higher than the best discrete time transversal MWP filter reported to-date.