title: Ultra-wide free spectral range, enhanced sensitivity, and removed mode splitting SOI optical ring resonator with dispersive metal nanodisks.
abstract: A refractive index sensor with a free spectral range that is unlimited by neighboring mode spacing (10 fold increase with respect to 20 nm of an unmodified ring), based on an optical silicon-on-insulator microring resonator patterned with periodically arranged set of gold nanodisks, is presented and numerically verified. It is shown that the particular periodic arrangement of nanodisks selects a single resonance from a wide set of ring resonator modes and removes mode splitting. Extraction of the waveguided electromagnetic energy into evanescent plasmonic modes enhances light-analyte interaction and increases device sensitivity to variation of refractive index up to 176  nm/RIU (about 2-fold increase compared to the unmodified ring), which is useful for sensor applications. Proof of the concept is presented by finite-difference time-domain simulations of a design readily practicable by means of modern nanotechnology.
authors.forename: Darius
authors.initials: D
authors.lastname: Urbonas
authors.forename: Armandas
authors.initials: A
authors.lastname: Balčytis
authors.forename: Martynas
authors.initials: M
authors.lastname: Gabalis
authors.forename: Konstantinas
authors.initials: K
authors.lastname: Vaškevičius
authors.forename: Greta
authors.initials: G
authors.lastname: Naujokaitė
authors.forename: Saulius
authors.initials: S
authors.lastname: Juodkazis
authors.forename: Raimondas
authors.initials: R
authors.lastname: Petruškevičius
mesh_terms: D006046:Gold / Q000737:chemistry*; D049329:Nanostructures; D055096:Optical Devices; D012825:Silicon; D013057:Spectrum Analysis
chemical_list: D006046:Gold; D012825:Silicon