Nanostructured Surfaces for Controlling Absorption and Thermal Radiation

Styring af Absorption og Termisk Udstråling med Nanostrukturerede Overflader

Odgaard, Michael ; Laursen, Mads Goldschmidt

4. term

Nanotechnology, Master

2014

2014-06-04

82

I dette speciale undersøger vi, hvor meget lys der reflekteres fra rækker af ultraskarpe, regelmæssige riller i en guldoverflade for lys, der kommer fra vilkårlige retninger – også når lyset udbreder sig langs rillerne. Disse strukturer er interessante, fordi deres absorption kan indstilles selektivt, hvilket gør dem lovende til vedvarende energiteknologier som termofotovoltaik og koncentreret solenergi. Vi præsenterer to effektive numeriske modeller: (1) en enkel, tilnærmet stack-matrix-metode, der bruger modeindekset for gap-plasmon-polaritoner (G-SPP'er) som et effektivt indeks, og (2) en stringent Green's Function Surface Integral Equation Method (GFSIEM), en fuld elektromagnetisk beregning. På trods af sin enkelhed giver stack-matrix-metoden resultater, der ligner de præcise resultater fra GFSIEM bemærkelsesværdigt meget. Det understøtter, at absorptionen i disse rillestrukturer i høj grad styres af, hvordan indkommende lys kobles til plasmoner.

This thesis examines how much light is reflected by arrays of ultra-sharp, regularly spaced grooves in a gold surface, for light arriving from any direction—including along the grooves. These structures are attractive because their absorption can be tuned to select specific colors, making them promising for renewable energy technologies such as thermophotovoltaics and concentrated solar power. We present two efficient numerical models: (1) a simple, approximate stack-matrix method that uses the mode index of gap-plasmon polaritons (G-SPPs)—electromagnetic waves confined in narrow gaps and coupled to electron oscillations—as an effective index, and (2) a rigorous Green's Function Surface Integral Equation Method (GFSIEM), a full electromagnetic calculation. Despite its simplicity, the stack-matrix method closely matches the precise results from GFSIEM. This supports the conclusion that absorption in these groove arrays is largely governed by how incoming light couples into plasmons.

[This abstract was generated with the help of AI]

plasmonic black metal ; PBM ; Green's function ; Green ; Green's ; Green function ; GFSIEM ; absorption ; plasmon ; plasmonics ; surface plasmon ; surface plasmon polariton ; gap surface plasmon polariton ; SPP ; G-SPP ; GSPP ; stack matrix ; transfer matrix ; numerical modelling ; numerical simulations ; thermal emission ; ultra-sharp grooves ; sharp grooves ; general direction of light incidence ; periodic structures

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