Recently, the National Key Laboratory of Sensor Technology, housed within the Shanghai Institute of Microsystem and Information Technology of the Chinese Academy of Sciences, has made a significant breakthrough by successfully developing a hybrid integrated gas-sensing silicon photonic chip. This innovative chip integrates fluorescent sensing films with optical micro-ring resonators, overcoming the limitations of traditional fluorescent gas sensors in sensitivity and selectivity. This leap forward is attributed to a chemical-optical dual-mode synergistic signal amplification mechanism.

The research team tackled prevalent issues in mainstream silicon nitride straight waveguide structures, such as low fluorescence excitation efficiency and poor signal collection efficiency. They proposed a micro-ring resonator enhancement scheme based on silicon-based photonic integrated chips. This approach leverages the spectral modulation capabilities of the micro-ring resonator to transform broadband fluorescence emissions into discrete, high-quality factor resonance peaks. This transformation not only enhances the signal-to-noise ratio but also preserves the spectral fidelity of the output signals.

By delving into the synergistic dual-mode response mechanism—where optical refractive index changes and chemically induced fluorescence intensity quenching occur simultaneously during gas detection—the team achieved substantial improvements in sensing performance. Experimental data reveal that the chip can detect gas concentrations as low as 1.25 parts per billion (ppb). The enhanced sensitivity stems from the amplification effect of resonant wavelength shifts on the fluorescence intensity decrease caused by quenching. Crucially, the two independent physical signals—fluorescence intensity and resonant wavelength—can corroborate each other. This mutual verification enhances identification accuracy through multi-dimensional criteria, effectively addressing the challenge of distinguishing gases with similar fluorescence quenching behaviors.

Furthermore, the study established a theoretical model to elucidate the synergistic mechanism for the first time and validated the universality of this method across multiple fluorescent probes.