Research on sensing characteristics of diamond multilayer waveguide structure racetrack micro-ring resonator

A racetrack micro-ring resonant cavity sensor based on the diamond's material is proposed in this paper. In the model, the vertical-section of the waveguide adopts a five-layer ridge-type waveguide structure based on CH3NH3PbI3, SiO2 and diamond, i.e. CH3NH3PbI3-SiO2-Diamond-SiO2-CH3NH3PbI3. First, on the basis of the resonant principle and coupled mode theory, this study investigated the light field intensity distribution characteristics of the integral resonant cavity, the longitudinal section of a single straight waveguide, the racetrack micro-ring, and the longitudinal section of the straight waveguide by using the finite element method in COMSOL. The analysis shows that the introduction of CH3NH3PbI3 as an isolation layer can avoid the light scattering loss and leakage loss, and significantly enhance the filtering performance. In addition the sensing characteristics of the Add-drop racetrack resonator were further studied. Results showed that the structure could achieve a quality factor of 10(5), and the sensitivity could reach 14833.33 dB/RIU. In the detection system with a signal-to-noise ratio of 30 dB, the detection limit was 2.02 x 10(-7) RIU. Compared with the traditional All-pass single micro-ring resonator, the proposed structure shows advantages of high tenability, high sensitivity and low detection limit.