Comparison of Resonant Plasmon Polaritons with Mie Scattering for Laser-Induced Near-Field Nanopatterning: Metallic Particle vs Dielectric Particle

In this paper we describe a comparative study of near-field surface nanopatterning using metallic and dielectric nanoparticles excited by an 820 nm near-infrared femtosecond laser. It is found that the existing understanding that a metallic particle generates a larger near-field than a dielectric particle when the particle size is smaller than the illumination wavelength is NOT always correct. Concerning near-field enhancement on low-refractive-index substrates, the enhancement factor for an appropriate dielectric particle in the TE1 (magnetic dipole) resonance mode is found to be higher than that induced by a gold particle even in the TM1 (electric dipole) resonance mode of a gold particle. Conversely, on a high-refractive-index substrate such as silicon, the near-field enhancement factor is larger using a gold particle with the same particle size. This result will be useful for selecting the best combination of substrate and nanoparticle material for laser-induced nanoparticle-mediated optical near-field patterning. (C) 2009 The Japan Society of Applied Physics