Analytic description of channel plasmon polaritons.

Using the effective-index approximation along with the explicit expression for the propagation constant of gap surface plasmons established recently [Opt. Express16, 2676 (2008)], we derive closed-form expressions for channel plasmon polariton (CPP) modes supported by V grooves cut into metal. The CPP field distributions and mode characteristics are calculated for the air-gold configuration. The results obtained are found to be in good agreement with the results of previous numerical simulations.