Plasmonic Bowtie Nanoantenna: Gap Field Enhancement

A bowtie nanoantenna is two triangular metal nanostructures tip-to-tip across a gap only a few nanometres wide. Light drives the free electrons in each wing into a localized surface plasmon resonance, and the sharp facing tips funnel that oscillating charge into an intensely concentrated "hot spot" field in the gap — the effect behind surface-enhanced Raman spectroscopy and single-molecule optical sensing. This simulator models each wing as a driven, damped harmonic oscillator: tune the wing length and material to shift the resonance wavelength, shrink the gap to boost the geometric field concentration, sweep the drive wavelength through resonance, and rotate the incident polarization to watch the coupling strength follow a cos²θ law — all with live-updated resonant wavelength, field-enhancement factor and quality-factor readouts.