Synergistic Dual‐Mode Amplification in Hybrid Integrated Sensing Chip for Ultrasensitive and Discriminative Gas Detection

ABSTRACT

Integrating fluorescence sensing with silicon photonic platforms holds great potential for on‐chip molecular detection, but so far it is hindered by weak waveguide‐collected fluorescence and unreliable spectral information. We propose and demonstrate an on‐chip fluorescence sensing paradigm by hybrid integrating fluorescent materials with silicon‐on‐insulator (SOI) microring resonators. Unlike integrating with straight waveguides, the microring resonator modulates broadband fluorescence into discrete high‐quality (Q = 3476.7) resonant peaks, concurrently enhancing signal‐to‐noise ratio (SNR) and spectral fidelity. This modulation enables a synergistic dual‐mode amplification mechanism within a single microring resonator: where the resonance wavelength shift from refractive‐index variations and the intensity quenching from chemical responses cooperate to mutually boost the sensing output. It is first experimentally demonstrated in an SOI based on‐chip sensor with a 1 ppb detection limit, accompanied by the first theoretical model clarifying this synergistic effect. Beyond sensitivity enhancement, the dual‐mode synergy provides multi‐dimensional discriminative parameters (wavelength shift, peak intensity variation, and overall fluorescence intensity variation), fundamentally improving sensing accuracy for gas species with similar fluorescence quenching behaviors. This work offers a promising route to a high‐performance on‐chip fluorescence sensor via a standard SOI‐compatible technique.