Thursday 20th of October at 14.30 in Aula Seminaria di Fisica,  Foroogh Sarbishe Khozeymeh (University of Kurdistan Hewler, Iran) will give a talk on WGM Optical Biosensors

Abstract: Optical biosensors are a class of sensors exploiting light for realization and detection of changes in biochemical environment. Light in interaction with biological tissues, usually doesn’t alter their characteristics and therefore it can detect spices without labor process of labeling. In the first part of this work, detailed theoretical analysis of the basic properties of whispering-gallery modes (WGMs) of cylindrical resonators as optical biosensors using  Lam’s approximation is demonstrated. Using obtained closed-form analytical equations, resonance wavelengths of higher radial and angular order WGMs of TE and TM polarization waves are calculated. It is shown that analytical and numerical calculations results, are in a good agreement. These results are well agreed with other experimental work. It is depicted that by extending proposed two layers resonator structure analyzing scheme, it is possible to study three layers cylindrical resonator structure as well. Using this method, sensing WGM internal and external caustic radii , which have a great importance in evanescent WGM sensing, are also obtained. Moreover, the sensitivity of the WGM resonances is analyzed as a function of the structural parameters of the cylindrical resonators. Based on the results higher radial order WGMs, at bigger radii of resonator, display more bulk refractive index sensitivity. In the second part of this work coupling characteristics of WGMs in a planar disk resonator, and effect of them in biosensing applications, is examined.