Tunable Fano-like resonance analysis based on a system consisting of a two-silica-microdisk-coupled Mach–Zehnder interferometer and graphene

Abstract

We theoretically demonstrate a significant system to realize asymmetric Fano-like resonance by coupling two silica microdisks with a fiber Mach–Zehnder interferometer (MZI), which could also be modulated by graphene with the electro-optic effect. The microdisks are respectively and evanescently coupled with the two arms of the MZI. Depending on the coupling strength between the microdisks and the fiber tapers, the diameters of the microdisks, and the quality factors of the microdisks, transmission spectra of the MZI exhibit the resonance peak, the resonance dip, and the Fano-like resonance. In addition, by introducing the graphene with the electro-optic effect, the quality factor and resonant wavelength of one microcavity are modulated, consequently also varying the Fano-like line shapes. This asymmetric Fano-like resonance with the advantages of fiber or waveguide integration, ease of operation, and convenient controllability of line shape could have great potential in high-performance sensing, optical switching, and optical signal processing.