Research Project: Yüksek Dereceli Merkezi Sinir Sistemi Tümörü Hastalarında Tümör Doku Kesitlerinde ve Serumda Meydana Gelen Moleküler Değişikliklerin SERS (Surface Enhanced Raman Spectroscopy) ile Belirlenmesi ve Hastalığın Tanısında Kullanılmasının Gösterilmesi
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Contributors
Funders
ID
TB.00465
Authors
Solaroğlu, İhsan
Faculty Member
Publications
Genetic algorithm-driven surface-enhanced Raman spectroscopy substrate optimization
(Multidisciplinary Digital Publishing Institute (MDPI), 2021) Bilgin, Buse; Onbaşlı, Mehmet Cengiz; Torun, Hülya; Yanık, Cenk; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; KUTTAM (Koç University Research Center for Translational Medicine); Yes; College of Engineering; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING; Research Center
Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive and molecule-specific detection technique that uses surface plasmon resonances to enhance Raman scattering from analytes. In SERS system design, the substrates must have minimal or no background at the incident laser wavelength and large Raman signal enhancement via plasmonic confinement and grating modes over large areas (i.e., squared millimeters). These requirements impose many competing design constraints that make exhaustive parametric computational optimization of SERS substrates pro-hibitively time consuming. Here, we demonstrate a genetic-algorithm (GA)-based optimization method for SERS substrates to achieve strong electric field localization over wide areas for recon-figurable and programmable photonic SERS sensors. We analyzed the GA parameters and tuned them for SERS substrate optimization in detail. We experimentally validated the model results by fabricating the predicted nanostructures using electron beam lithography. The experimental Raman spectrum signal enhancements of the optimized SERS substrates validated the model predictions and enabled the generation of a detailed Raman profile of methylene blue fluorescence dye. The GA and its optimization shown here could pave the way for photonic chips and components with arbitrary design constraints, wavelength bands, and performance targets.
Broadband enhancement of Faraday effect using magnetoplasmonic metasurfaces
(Springer, 2020) Kharratian, Soheila; Onbaşlı, Mehmet Cengiz; Ürey, Hakan; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Yes; College of Engineering; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING
Magnetooptical Faraday effect enables ultrafast photonic devices based on nonreciprocal polarization rotation; however, the intrinsic weakness of Faraday effect prevents miniaturization and practical applications of nonreciprocal photonic devices. Magnetoplasmonics offers new mechanisms for enhancing magnetooptical effects using surface plasmon resonances, which generally have narrow bandwidths. Using finite-difference time-domain modeling, we demonstrate a magnetoplasmonic metasurface, which remarkably enhances the Faraday effect in a wide spectral range. While Faraday rotation in a bare bismuth-substituted yttrium iron garnet film is below 0.02 degrees in the studied range of 600-1600 nm, the proposed metasurface yields few degrees of rotation in a broad band with a maximum exceeding 6.5 degrees, which indicates about three orders of magnitude enhancement. We also show that by optimizing the configuration of the system including the geometry and excitation parameters, the metasurface response and operation band can be tuned further, and rotation values higher than 20 degrees can be achieved. Finally, we present guidelines for designing magnetoplasmonic metasurfaces.
