Double-Layer Dielectric Microdisk Resonator Based Refractive Index Sensing Characteristics

Aims: A double-layer dielectric microdisk resonator is proposed. Its refractive index (RI), sensing characteristics, temperature, compensation are studied. Method: By using 3D-finite element method (3D-FEM), the modes and transmission response of the double-layer dielectric microdisk resonator are investigated. Observations: According to the transmission response, there is a critical coupling status when the coupling gap is ~50 nm. With the increasing of the thickness ratio of the polydimethylsiloxane (PDMS) to that of the Si layers, the waveguide sensitivity of RI and temperature decrease sharply, and then changes slowly when the thickness ratio is more than 0.5. Result: The RI sensitivity and detection limit (DL) are ~25 nm/RIU and ~1.1×10-3 RIU, respectively. Conclusion: Compared to traditional microdisk resonator, the double-layer dielectric microdisk resonator achieves temperature compensation due to the upper PDMS layer.