Plasmonic Nanofocusing: Adiabatic Tip Compression

Nanophotonics is largely the study of squeezing light into spaces far smaller than its own wavelength, and adiabatic plasmonic nanofocusing is one of the cleanest ways it happens: launch a surface plasmon polariton down a gradually tapered metal wire or tip, and as the local radius shrinks toward the metal's skin depth the mode's effective index climbs, its wavelength compresses, and its energy piles up into a nanometre-scale hot spot at the apex. This simulator computes the Drude-model dielectric function for gold or silver, solves the flat-interface SPP dispersion relation, and applies the adiabatic-taper approximation to drive a live 3D visualization — tune the metal, driving wavelength, base radius and taper angle, then send a wave pulse and watch the ring spacing shrink and the apex glow brighten exactly as the governing equations predict.