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 similar to 100 mu m) and well-confined (mode width congruent to 1.1 mu m) CPP guiding along a triangular 0.6 mu m-wide and 1 mu m-deep groove in gold. We develop a simple model based on the effective-index method that accounts for the main features of CPP guiding and provides a clear physical picture of this phenomenon.