title: A highly sensitive refractometric sensor based on cascaded SiN microring resonators.
abstract: We investigate a highly sensitive optical sensor based on two cascaded microring resonators exploiting the Vernier effect. The architecture consists of two microrings with a slight difference in their free spectral ranges. This allows the generation of the Vernier effect for achieving ultra-high sensitivities. The sensor chip was fabricated using a silicon nitride platform and characterized with isopropanol/ethanol mixtures. A sensitivity of 0.95 nm/% was found for isopropanol concentrations in ethanol ranging from 0% to 10%. Furthermore, a collection of measurements was carried out using aqueous sodium chloride (NaCl) in solutions of different concentrations, confirming a high sensitivity of 10.3 nm/% and a bulk refractive index sensitivity of 6,317 nm/RIU. A limit of detection of 3.16 × 10(-6) RIU was determined. These preliminary results show the potential features of cascaded silicon nitride microring resonators for real-time and free-label monitoring of biomolecules for a broad range of applications.
authors.affiliation: Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute, Einsteinufer 37, Berlin 10587, Germany. vanyzg81@gmail.com.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Zamora
authors.forename: Peter
authors.initials: P
authors.lastname: Lützow
authors.forename: Martin
authors.initials: M
authors.lastname: Weiland
authors.forename: Daniel
authors.initials: D
authors.lastname: Pergande
mesh_terms: D019840:2-Propanol / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry; D057230:Limit of Detection; D012031:Refractometry / Q000295:instrumentation* / Q000379:methods; D017655:Silicon Compounds / Q000737:chemistry*; D012965:Sodium Chloride
chemical_list: D017655:Silicon Compounds; D000431:Ethanol; D012965:Sodium Chloride; D019840:2-Propanol; C032734:silicon nitride