Print Email Facebook Twitter Dielectric Metasurface Designs for Surface Enhanced Raman Scattering with Large Distances between Nanoparticles Title Dielectric Metasurface Designs for Surface Enhanced Raman Scattering with Large Distances between Nanoparticles Author Dekker, Jeroen (TU Delft Mechanical, Maritime and Materials Engineering) Contributor Rieger, B. (mentor) Gerini, Giampiero (graduation committee) Degree granting institution Delft University of Technology Programme Applied Sciences Date 2023-07-12 Abstract In this thesis new dielectric metasurfaces in immersion were explored with a periodic distribution of unit cells with multiple silicon cylinder structures on a reflective gold slab with a fused quartz spacer in between. These new metasurfaces were designed with 60 nm and 130 nm gaps in order to improve manufacturability and enable larger particles to enter the hotspot region while trying to maintain high electric field enhancement and enhancement factors. This was done by simulating the plane wave excitation in a range of 750 nm to 850 nm for a large number of metasurfaces using electromagnetic modelling software Lumerical using its finite difference time domain method. After exploring multiple silicon cylinder structures the focus was put on periodic metasurfaces with unit cells containing single, dimer, and quadrumer positioning of cylinders and enhancement factors of between 500-2000 were found. Afterwards the found fields for new promising designs were used in an optical trapping algorithm were enhancement factors for 10 nm particles were found between 10^4-10^5 and for 40 nm particles between 10^3-10^4. The effect of exciting a metasurface with circular polarization for quadrumer structures was thoroughly investigated but yielded no better enhancement factor than previous dimer designs. A new optical trapping scheme where the laser intensity is increased near the end of optical trapping is proposed to give slight improvement of enhancement factors after trapping. Overall, the limitations of the electromagnetic simulations and optical trapping algorithm makes it difficult to assume the enhancement factors found are realizable in experiment. These limitations need to be addressed before any conclusions can be made on whether immersion SERS offers any advantages over dry SERS in the case of dielectric metasurfaces. Subject SERSDielectricRaman ScatteringDimerQuadrumerCircular polarizationImmersionOptical trappingLumerical To reference this document use: http://resolver.tudelft.nl/uuid:e49c84c3-c470-4d68-ac21-069d13a76498 Part of collection Student theses Document type master thesis Rights © 2023 Jeroen Dekker Files PDF Thesis_Dielectric_Metasur ... Dekker.pdf 10.63 MB Close viewer /islandora/object/uuid:e49c84c3-c470-4d68-ac21-069d13a76498/datastream/OBJ/view