Optical Response of Gold Nanoparticles: FDTD Simulation for Plasmonic Nanobubble Generation

Institute

Lehrstuhl für Thermodynamik (TUM-ED)

Type

Master's Thesis /

Content

 

Description

Background

Gold nanoparticles (Au NPs) strongly absorb near-infrared and visible light through localized surface plasmon resonance (LSPR). Under femtosecond laser irradiation, the absorbed optical energy is rapidly converted into heat, which can superheat the surrounding water layer and generate transient nanobubbles — a mechanism with direct applications in photothermal cancer therapy and drug delivery.

Quantifying the optical properties of the Au NP (absorption cross-section σ_abs, near-field enhancement) is a prerequisite for accurate molecular dynamics (MD) simulations of this heating process. The absorption cross-section determines how much laser energy is deposited per pulse, and the near-field enhancement governs the local intensity at the particle surface.

Objectives

This project aims to perform systematic Finite-Difference Time-Domain (FDTD) simulations of Au NPs in water to:

1. Calculate the absorption and scattering cross-sections as a function of wavelength (300–800 nm) for spherical Au NPs of radius 2–10 nm.

2. Identify the peak absorption wavelength and the corresponding absorption efficiency Q_abs = σ_abs / (πr²)

3. Map the near-field electric field enhancement |E/E₀|² around the NP surface at resonance

4. Validate results against Mie theory analytical solutions

5. Assess the sensitivity of σ_abs to NP radius, surrounding medium refractive index, and laser polarization

Methods

Primary software: Ansys Numerical FDTD. 

Alternative: MEEP (open-source, Python interface).

Requirements

- MSc student in Physics, Mechanical Engineering, Electrical Engineering, or related field

- Basic familiarity with electromagnetism (Maxwell's equations)

- Experience with simulation or programming tools (Python, MATLAB, or similar)

- Prior exposure to FDTD or computational photonics is a plus, but not required

Possible start

immediately

Contact

M.Sc. Zhao Song
Room: 5507.EG.727
Phone: +49 89 289 16197
z.songtum.de