Silicon nanoparticle Mie resonance calculator

When the wavelength inside the silicon (λ/n, with n ≈ 3.5–4) is about the particle's diameter, the field inside drives a circulating displacement current: a magnetic dipole. It is the lowest-energy Mie resonance of a high-index sphere, at about 467 nm for 100 nm, 580 nm for 140 nm and 770 nm for 200 nm silicon spheres in air (table above), with the electric dipole at shorter wavelengths.

Their Mie resonances scatter one band of colours strongly, so in a dark-field microscope or on a surface they shine in vivid structural colours that move from blue (about 100 nm) through green and yellow to red (about 200 nm) as the size grows: no dyes, no plasmons, and almost no absorption.

About 4.1 at 550 nm, 3.9 at 633 nm and 3.6 at 1000 nm, with absorption that drops steeply from the blue to the near-infrared (band gap 1.12 eV, about 1100 nm). The calculators use the measured data of Green (2008); Aspnes & Studna (1983) is available as an alternative.

Silicon resonances absorb little above about 500 nm, so they scatter efficiently without heating; they support magnetic as well as electric resonances, which allows directional (Kerker) scattering and Huygens metasurfaces. Gold gives stronger near-field enhancement and efficient heating, but with absorption losses.

Yes. Silicon is in every calculator: near-field maps (the magnetic-dipole field inside the particle), arrays and lattice resonances, particles on a silicon substrate, emitters near silicon and laser heating.