Paradoxes in laser heating of plasmonic nanoparticles

Abstract

We study the problem of the laser heating of plasmonic nanoparticles and demonstrate that, in sharp contrast to the common belief, a particle with a small dissipative constant absorbs much more energy than the particle with a large value of this constant. Even higher effective absorption may be achieved for core–shell nanoparticles. Our analysis uses the exact Mie solutions, and optimization of the input energy is performed at a fixed fluence with respect to the particle size, wavelength and duration of the laser pulse. We introduce a new quantity, the effective absorption coefficient of a particle, which allows one to compare quantitatively the light absorption by nanoparticles with that of a bulk material. We describe a range of parameters where a giant absorption enhancement can be observed and give practical examples of metals whose optical properties vary from weak (potassium) to strong (platinum) dissipation.