Mode-division multiplexing in a hybrid plasmonic-photonic resonator for low-crosstalk dual-species sensing

Traditional discrete humidity and hydrogen sensors suffer from large footprints and cross-interference, limiting applications in hydrogen-fueled systems and semiconductor manufacturing. Here, we demonstrate a plasmonic-photonic hybrid resonator (PPHR) for low-crosstalk dual-parameter detection via mode-division multiplexing. It integrates a polyvinyl alcohol (PVA)-guided mode resonance for humidity sensing and a Pd-Au plasmonic resonance for hydrogen sensing, yielding analyte-specific modes with strong spectral separation. Humidity is monitored from the guided-mode redshift induced by PVA swelling and refractive-index variation, whereas hydrogen is detected from the plasmonic-resonance blueshift caused by hydrogen-induced phase change in palladium (Pd). Simulations show negligible crosstalk between the two independent working modes. This platform provides a practical route to integrated real-time multiparameter optical sensing.