Micro optical sensing using dielectric resonators

The purpose of this study is to develop an analytic approach for predicting Morphology Dependent Resonances (MDR) in dielectric microcavities (microsphere and microcylinder). Polarized electromagnetic waves, Transverse Electric (TE) and Transverse Magnetic (TM), are considered to analyze MDR. New asymptotic solutions have been developed based on electromagnetic theory derivations at the large size parameter (pi times diameter divided by wavelength of light) limits. The resonance conditions are characterized both theoretically and experimentally for both dielectric microsphere and microcylinder by considering the fact that the size parameter of the microcavities is very large at optical wavelengths.;The theoretical development is mathematically robust and significantly less complicated than existing approaches presented in the literature. The theoretical result of size parameter for consecutive MDR peaks are validated by experimental data obtained via this study using a tunable semiconductor laser and from data available from the literature. The comparisons are shown to be accurate for large size parameters. The quality factor of experimental resonance spectra observed in the laboratory is calculated approximately in the order of 104 which is sensitive enough to detect micro or nano level temperature changes in the surrounding medium. The sensitivity of the developed MDR temperature sensor is wavelength change of 0.045 nm (10-9 meter) for one degree centigrade change in temperature. The sensitivity of optical thermal deformation sensor based on WGM resonance is measured to be 57 nm/ 0C which means molecular level (Angstrom, Å´) deformation due to one degree centigrade temperature change in the surrounding can be detected with proposed optical thermal deformation sensor. The proposed sensors could potentially be used for nano technology, Micro-Electro-Mechanical Systems (MEMS) devices, biomedical and aerospace applications.