Nanometer-sized optical waveguides fabricated by anodic oxidation using a scanning near-field optical microscope

We have fabricated an optical waveguide with a subwavelength cross section that propagates light. A metal–oxide core is partially embedded into a metal clad by anodic oxidation using the probe tip of a scanning near-field optical microscope (SNOM). Then, using the SNOM in transmission mode we have evidence of light propagating more than 5 μm in the waveguide whose core width and thickness are 300 and 70 nm, respectively.