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A Highly Sensitive Refractometric Sensor Based on Cascaded SiN Microring Resonators
Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute, Einsteinufer 37, Berlin 10587, Germany
* Author to whom correspondence should be addressed.
Received: 19 August 2013; in revised form: 18 October 2013 / Accepted: 24 October 2013 / Published: 28 October 2013
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.
Keywords: microring resonators; refractometric sensors; Vernier effect; silicon nitride; integrated optical devices
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Zamora, V.; Lützow, P.; Weiland, M.; Pergande, D. A Highly Sensitive Refractometric Sensor Based on Cascaded SiN Microring Resonators. Sensors 2013, 13, 14601-14610.
Zamora V, Lützow P, Weiland M, Pergande D. A Highly Sensitive Refractometric Sensor Based on Cascaded SiN Microring Resonators. Sensors. 2013; 13(11):14601-14610.
Zamora, Vanessa; Lützow, Peter; Weiland, Martin; Pergande, Daniel. 2013. "A Highly Sensitive Refractometric Sensor Based on Cascaded SiN Microring Resonators." Sensors 13, no. 11: 14601-14610.