Plasmonic subwavelength waveguides: next to zero losses at sharp bends

We demonstrate that approximately 100% transmission of a strongly localized channel plasmon polariton can be achieved through a sharp 90 degrees bend in a subwavelength waveguide in the form of a triangular groove on a metal surface--a feature that has previously been demonstrated only for photonic crystal waveguides, which do not provide subwavelength localization. Conditions for minimum reflection and radiative losses at the bend are investigated numerically by the finite-difference time-domain algorithm. Dissipation in the structure is demonstrated to be sufficiently low to ensure significant propagation distances (a number of wavelengths) of the localized plasmon in each of the arms of the bend.