  Fano resonance exhibiting an asymmetric spectral line shape is a universal
phenomenon observed in diverse physical systems. Here we experimentally
establish a direct link between the spectral asymmetry parameter and a
physically realizable phase factor of interference between a continuum and a
discrete mode that leads to Fano resonance. Using a specially designed
metamaterial, namely waveguided plasmonic crystal with a spatially varying
orientation axis of plasmonic grating, we demonstrate control on the spectral
asymmetry of the Fano resonance through changes in the geometric phase of
polarized light. In this scenario, the changes in the geometric phase for input
left, and right circular polarized light arises due to varying orientation
angle of the grating axis. The systematic changes in the geometric phase and
the resulting q-parameter of Fano resonance is interpreted by an appropriate
theoretical model connecting the two physical entities. The demonstrated
control over the spectral line shape of Fano resonance achieved by tailoring
geometric phase may open up novel routes for polarization-based photonic
applications.
