Propagation of surface plasmon polariton in nanometre-sized metal-clad optical waveguides.

Using a local anodic-oxidation method with a probe tip of a scanning near-field optical microscope (SNOM) as the electrode, we have fabricated an oxide core with subwavelength dimensions on metal. The propagation of the surface plasmon polariton (SPP), which is excited at the interface between the oxide core and the metal clad, has been investigated using the same SNOM. Altering the wavelength of input light from 532 nm to 830 nm, the propagation length of the SPP extends from 2 micro m to 6 micro m. We carried out a simulation of the SPP propagation, and obtained a similar wavelength dependence.