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Register a new userFano resonance lineshapes in a waveguide-microring structure enabled by an air-hole
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Added by
Xuetao Gan Prof. Dr.
Publication date
2019
fields
Physics
and research's language is
English
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We propose and demonstrate, by simply inserting an air-hole in the waveguide side-coupling with a microring resonator (MRR), the transmission spectrum presents Fano lineshapes at all of the resonant modes. Measured from the fabricated devices, Fano lineshapes with slope rates over 400 dB/nm and extinction ratios over 20 dB are obtained. We ascribe it to the air-hole-induced phase-shift between the discrete resonant modes of the MRR and the continuum propagating mode of the bus-waveguide, which modifies their interference lineshapes from symmetric Lorentzian to asymmetric Fano. From devices with varied locations and diameters of the air-hole, different Fano asymmetric parameters are extracted, verifying the air-hole-induced phase-shifts. This air-hole-assisted waveguide-MRR structure for achieving Fano resonance lineshapes has advantages of simple design, compact footprint, large tolerance of fabrication errors, as well as broadband operation range. It has great potentials to expand and improve performances of on-chip MRR-based devices, including sensors, switchings and filters.
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Microring resonators, as a fundamental building block of photonic integrated circuits, have been well developed into numerous functional devices, whose performances are strongly determined by microrings resonance lineshapes. We propose a compact structure to reliably realize Lorentzian, Fano, and electromagnetically induced transparency (EIT) resonance lineshapes in a microring. By simply inserting two air-holes in the side-coupled waveguide of a microring, a Fabry-Perot (FP) resonance is involved to couple with microrings resonant modes, showing Lorentzian, Fano, and EIT lineshapes over one free spectral range of the FP resonance. The quality factors, extinction ratios, and slope rates in different lineshapes are discussed. At microrings specific resonant wavelength, the lineshape could be tuned among these three types by controlling the FP cavitys length. Experiment results verify the theoretical analysis well and represent Fano lineshapes with extinction ratios of about 20 dB and slope rates over 280 dB/nm. The reliably and flexibly tunable lineshapes in the compact structure have potentials to improve microring-based devices and expand their application scopes.
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