Silica polygonal micropillar resonators: fano line shapes tuning by using a Mach-Zehnder interferometer

We experimentally demonstrate Fano resonance line shapes tuning by using a Mach-Zehnder interferometer (MZI). We employ a silica 125-μm-size hexagonal micropillar resonator with prism coupling in one arm of the interferometer, and a phase shifter together with a variable attenuator in the other arm. Our initial experiments reveal that the resonance line shapes observed at the interferometer output are characteristically asymmetric as Fano resonances. By using the phase shifter, we controllably tune the asymmetric line shapes from near-symmetric dip to near-symmetric peak and back to near-symmetric dip. We discuss potential applications of our MZI-based microresonator resonance line shapes tuning for bio-chemical sensing.