Edge diffraction, plasmon launching, and universal absorption enhancement in two-dimensional junctions

Exact solutions to diffraction problems in wave optics are scarce though strongly demanded for accurate knowledge of electromagnetic fields the immediate vicinity scatterers. Here, we obtain and analyze an exact analytical solution plane-wave at a lateral junction two-dimensional (2D) conductors with dissimilar surface conductivities. We find that near possesses dipolelike radiative component 2D surface-plasmon polaritons launched by edge. show between perfect metal ohmic conductor enhances local absorbance, which is ratio absorbed power density light intensity. It reaches universal value 200% edge normal incidence, independent absorbance bulk. A also acts as efficient coupler photons plasmons. Its amplitude conversion efficiency demonstrates unbounded growth increase impedance. Our results set fundamental limits field enhancement edges should change strategies design subwavelength radiation detectors.