High- Q Mie resonators for refractive-index sensing

Refractive-index sensors have been used in a wide range of applications, including biological diagnosis and therapy, material analysis and shaping, (bio)chemical sensing, environmental monitoring, and many more. A good sensor should have sufficiently high sensitivity and figures of merit to detect the slightest changes in the environment. Here, we study the performance of high-Q Mie modes of dielectric cylinders with ultrahigh permittivity for refractive-index sensing. First, we experimentally demonstrate the emergence of high-Q Mie modes in the scattering spectrum of a single dielectric cylinder with ultrahigh permittivity (ε≈40--100). We also investigate the sensitivity of the high-Q Mie modes to the background refractive index of the surrounding environment. The simulation results demonstrate that the high-Q Mie modes are sensitive to changes in the surrounding refractive index. This results in high sensitivities and remarkable figures of merit, indicating their potential for refractive-index sensing applications. However, the material losses limit the observation of high-Q modes and their sensing capability.