Tunable ring-coupled Mach-Zehnder interferometer based on lithium niobate

The fabrication and characterization are reported of a Fano resonance-based electro-optically tunable ring resonator-coupled Mach-Zehnder interferometer device based on a chalcogenide-lithium niobate hybrid waveguide system. The experiments reveal inherent asymmetric lineshapes that can be flipped to a near symmetrical resonance by applying a dc voltage of ~10 V across the electrode at the MZI non-resonator arm. Further increase in voltage yields the reverse of initial asymmetry. The optical filter-based transfer-matrix model easily explains the experimental data and indicates ways to further enhance the usability of such architecture.