Channel Plasmon-Polariton Guiding by Subwavelength Metal Grooves

We report on realization of channel plasmon-polariton (CPP) propagation along a subwavelength metal groove. Using imaging with a near-field microscope and end-fire coupling with a tapered fiber connected to a tunable laser at telecommunication wavelengths (1425--1620 nm), we demonstrate low-loss (propagation length $\ensuremath{\sim}100\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$) and well-confined (mode width $\ensuremath{\cong}1.1\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$) CPP guiding along a triangular $0.6\text{ }\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$-wide and $1\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$-deep groove in gold. We develop a simple model based on the effective-index method that accounts…