Sensitivity optimization in whispering gallery mode optical cylindrical biosensors

Abstract

Abstract. Whispering-gallery-mode resonances propagated in cylindrical resonators have two angular and radial orders of l and i. In this work, the higher radial order whispering-gallerymode resonances, (i = 1 − 4), at a fixed l are examined. The sensitivity of theses resonances is analysed as a function of the structural parameters of the cylindrical resonator like different radii and refractive index of composed material of the resonator. A practical application where cylindrical resonators are used for the measurement of glucose concentration in water is presented as a biosensor demonstrator. We calculate the wavelength shifts of the WG1-4, in several glucose/water solutions, with concentrations spanning from 0.0% to 9.0.% (weight/weight). Improved sensitivity can be achieved using multi-WGM cylindrical resonators with radius of R = 100 μm and resonator composed material of MgF 2 with refractive index of nc = 1.38. Also the effect of polarization on sensitivity is considered for all four WGMs. The best sensitivity of 83.07 nm/RIU for the fourth WGM with transverse magnetic polarization, is reported. These results propose optimized parameters aimed to fast designing of cylindrical resonators as optical biosensors, where both the sensitivity and the geometries can be optimized.

Hollow-Core Fiber-Based Biosensor: A Platform for Lab-in-Fiber Optical Biosensors for DNA Detection

“…In this scheme of detection, the bio/chemical analytes are directly detected without the laborious process of analyte molecule labeling [ 10 , 11 , 12 ]. Regarding their transducer part, optical biosensors are categorized into different groups of resonator-based [ 13 , 14 , 15 ], waveguide-based [ 16 , 17 ], and interferometric-devices based [ 18 , 19 ]. Although these optical sensors have demonstrated high sensitivities for both bulk and surface sensing measurements [ 20 , 21 , 22 ], they still suffer from a critical issue.…”

Fast analytical modelling of an SOI micro-ring resonator for bio-sensing application

“…In particular, it has been shown that whispering gallery mode (WGM) resonators like ring resonators can be used as label-free biosensors [10][11][12]. Other geometries of WGM-resonator-based biosensors, like spherical [13,14], cylindrical [15][16][17], and disk structures [18,19], have emerged as alternative device geometries in biosensing. While WGM microsphere and microcylinder biosensors exhibit high quality factors, their circuit integration, mass production and reproducibility are extremely challenging [13].…”

“…In our previously published works, we have presented a simple analytical method for modelling of cylindrical resonator based biosensors [16,17]. Here, we use some fast analytical methods to analyze a SOI WGM ring resonator coupled to a straight waveguide.…”