Observation of weak value amplification in polarization-tailored Fano interference in waveguided plasmonic crystals

Resonance arising from the interference of a continuum and a discrete mode is known to give rise to a typical asymmetric spectral line shape and is called Fano resonance. We present a systematic study of Fano resonance in a variety of precisely designed wave guided plasmonic crystals that consists of metal nano-patterns deposited on ITO waveguide. Using a custom-designed dark field microscopy setup we record the Muller matrix spectrum of scattered light, that contains the entire polarization response of the device under study. We demonstrate large variation of the asymmetric line shapes of scattered light, tuned via pre- and post-selection of polarization states. We present a phenomenological model to quantify the dramatic control of spectral asymmetry in scattered intensity from Fano resonant systems in terms of physically accessible parameters of interference.The approach based on pre and post selection of optimized polarization states of light is further used to develop a novel concept of 'weak measurement' using the asymmetric spectral line shape of Fano resonance as a natural pointer generated within the system. The details of the results will be presented and their implications towards development of novel polarization controlled photonic devices will be discussed.