Tunable Fano-Like Resonance With Ultra-High Slope Rate via Nonlinear Interference in a Chalcogenide Microring Resonator

Fano resonances with a high extinction ratio (ER) and slope rate (SR), along with controllable tuning, are highly desired for important applications such as sensing and all-optical information processing. Here, we propose and experimentally demonstrate a tunable Fano-like resonance with an ultra-high SR, based on nonlinear interference within a single chalcogenide microring resonator (MRR). By tuning the relative phase of the involved waves with an external phase shifter, the transmission spectrum is dynamically reconfigured from a symmetric Lorentzian gain peak to Fano-like or electromagnetically induced transparency (EIT)-like lineshapes. Utilizing a chalcogenide MRR with a Q-factor exceeding 10 ⁶ , we achieve controllable Fano resonance with a remarkable ER of up to 35.3 dB, and an ultra-high SR of 2.5 × 10 ⁵ dB/nm, which is the highest one as compared to previous works. This result holds great potential for high-performance all-optical control and high-sensitivity sensing on a chip.