Wavelength Tuning of the Cylindrical Structure Whispering Gallery Mode Micro-Resonator for Sensing Applications

This study presented the utilization of wavelength tuning in cylindrical whispering gallery mode micro-resonators (WGMR) for sensing applications. A single-mode delivery optical fiber (18 μm diameter) and a sensor optical fiber (122 μm diameter) were employed. Two analytes, a sucrose liquid (with refractive indices ranging from 1.3472 to 1.3651 RIU) and a NaCl solution (with refractive indices ranging from 1.345 to 1.366 RIU), were used to tune the resonance wavelength. The sensitivities for analytes 1 and 2 were (-) 83 nm/RIU and (-)74 nm/RIU, respectively, with a Q-factor of 10⁴ for the proposed WGMR. The presented optical fiber sensor could improve the ability to detect various analytes with different refractive indices. Integrating this structure into a compact and portable sensing device could facilitate real-world applications where rapid and accurate detection of analytes, such as environmental monitoring and medical diagnostics, is required.