A critical analysis on the sensitivity enhancement of surface plasmon resonance sensors with graphene

The use of graphene in surface plasmon resonance sensors, covering a metallic (plasmonic) film, has a number of demonstrated advantages, such as protecting the film against corrosion/oxidation and facilitating the introduction of functional groups for selective sensing. Recently, a number of works have claimed that few-layer graphene can also increase the sensitivity of the sensor. However, graphene was treated as an isotropic thin film, with an out-of-plane refractive index that is identical to the in-plane index. Here, we critically examine the role of single and few layers of graphene in the sensitivity enhancement of surface plasmon resonance sensors. Graphene is introduced over the metallic film via three different descriptions: as an atomic-thick two-dimensional sheet, as a thin effective isotropic material (same conductivity in the three coordinate directions), and as an non-isotropic layer (different conductivity in the perpendicular direction to the two-dimensional plane). We find that only the isotropic layer model, which is known to be incorrect for the optical modeling of graphene, provides sizable sensitivity increases, while the other, more accurate, models lead to a negligible contribution to the sensitivity.This work was funded by FAPESP (grant nos. 2018/07276-5 and 2018/25339-4), the Brazilian Nanocarbon Institute of Science and Technology (INCT/Nanocarbon), and CAPES-PrInt (grant no. 88887.310281/2018-00). N.M.R.P. acknowledges PORTUGAL 2020, FEDER, and the FCT through projects: UIDB/04650/2020 strategic project, QML-HEP-CERN/FIS-COM/0004/2021 and PTDC/FIS-MAC/2045/2021, and the European Commission through the project GrapheneDriven Revolutions in ICT and Beyond (Ref. No. 881603, CORE 3).https://www.mdpi.com/2079-4991/12/15/256

Temperature Sensing Using Colloidal-Core Photonic Crystal Fiber

We report on a temperature sensor based on the monitoring of the luminescence spectrum of CdSe/ZnS nanocrystals, dispersed in mineral oil and inserted into the core of a photonic crystal fiber. The high overlap between the pump light and the nanocrystals as well as the luminescence guiding provided by the fiber geometry resulted in relatively high luminescence powers and improved optical signal-to-noise ratio (OSNR). Also, both core end interfaces were sealed so as to generate a more stable and robust waveguide structure. Temperature sensitivity experiments indicated a 70 pm/degrees C spectral shift over the 5 degrees C to 90 degrees C range

Successful fiber sensing technologies and hot topics for the near future

Inside the Photonics field Optical Fiber Sensors (OFS) are currently being used and will still be used in the future in a wide number of applications because its properties present technical advantages over traditional techniques or, sometimes, is practically the only feasible solution. In this paper, the more successful techniques will be reviewed. Then a prospective for the near future of the market and hot topics in which invest research resources will be suggested

Progress in the fabrication of the next-generation soft glass microstructured optical fibers

This paper was presented at the 1st Workshop on Specialty Optical Fibers and Their Applications, Sao Pedro, Sp, Brazil, 20-22 August, 2008.We report the fabrication of new soft glass microstructured optical fibers for sensing, high-nonlinearity and mid-infrared applications. The fibers were produced using the extrusion technique and a wide range of glass compositions. They demonstrate a wide variety of structural features and low propagation loss. © American Institute of Physics.Heike Ebendorff-Heidepriem, Roger C. Moore, and Tanya M. Monr

Applications of long period gratings in solid core photonic bandgap fibers

Solid core photonic bandgap fibres are photonic crystal fibres with a solid core surrounded by high index inclusions. The guidance properties of these fibers are very sensitive to the refractive index of the inclusions, making them widely tunable and making them very promising for sensing applications. Combining these fibers with long period gratings unleashes their full potential, enabling narrow band notch filters tunable over hundreds of nm, refractive index sensors with sensitivity comparable to that of surface plasmon resonance sensors, but also the extraction of the full band diagrams of these bandgap fibres

The inventory of geological heritage of the state of São Paulo, Brazil: Methodological basis, results and perspectives

An inventory of geological sites based on solid and clear criteria is a first step for any geoconservation strategy. This paper describes the method used in the geoheritage inventory of the State of São Paulo, Brazil, and presents its main results. This inventory developed by the geoscientific community aimed to identify geosites with scientific value in the whole state, using a systematic approach. All 142 geosites representative of 11 geological frameworks were characterised and quantitatively evaluated according to their scientific value and risk of degradation, in order to establish priorities for their future management. An online database of the inventory is under construction, which will be available to be easily consulted and updated by the geoscientific community. All data were made available to the State Geological Institute as the backbone for the implementation of a future state geoconservation strategy.The authors acknowledge the Science Without Borders Programme, Process 075/2012, which supported this study and the São Paulo Research Foundation (FAPESP), Process 2011/17261-6. We also thanks C. Mazoca for his help with maps and figures.info:eu-repo/semantics/acceptedVersio