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Computational Studies of Light-Nanoparticles Interactions – Kyle Belluomo

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REU student Kyle Belluomo (center) with his faculty mentor Prof. Matthew Pelton (left) and UMBC graduate student Haiku Leng (right) in Prof. Pelton’s laboratory.

My faculty mentor, Dr. Matthew Pelton, focuses on understanding what happens when light is incident upon nanoparticles. My summer research project involves computationally simulating the response of light (absorption and scattering) when incident upon a silver nanoparticle and on silver nanoparticle-based assemblies, through a variety of different software, such as MEEP, Lumerical, RSoft and Comsol.

Each software calculates the absorbance and scattering through computational electromagnetic methods. Meep, RSoft and Lumerical use a method called the Finite Difference Time Domain (FDTD). This method is popular when it comes to analyzing light and metal nanoparticle interactions, as it involves solving Maxwell’s Equations directly. A computational area is established that encompasses the metal nanoparticle to be studied, and this area is broken down into discrete time and space steps. Electric fields are initialized and propagated forward in space and time towards the structure of interest, and from this one can determine the localized field patterns around the object and subsequently the far-field patterns, which can in turn be used to determine scattering and absorption. Comsol uses the finite-element method, which also involves breaking the computational area down into discrete elements, but which solves Maxwell’s equations in the frequency domain rather than the time domain.

The goal of the project is to establish which software is most advantageous for us to use for future simulations of more complex metal nanoparticle systems, as each program comes with its own set of benefits and drawbacks. Eventually, we want to model a system where an assembly of gold nanoparticles is coupled to a quantum dot, as a graduate student is working on achieving the experimental measurements for such a system. We chose to start by simulating a silver nanoparticle, as the literature for this interaction is well established, so we will be able to confidently cross-reference our simulations to ensure we are achieving accurate results with the software. If I am successful in achieving reliable results and selecting a software package before the end of the summer, I will use the selected software to simulate an idealized system of coupled metal nanoparticles and quantum dots, towards the ultimate goal of simulating the exact system that is measured experimentally.

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Transmission (blue) and reflectance (green) of light when hitting a sphere with an arbitrary dielectric function. The data for this graph was achieved through a simulation in MEEP.