Confining light in a subwavelength thin optical waveguide

The size of optical components is typically limited by the fact that light cannot be confined to a volume with diameter smaller than the wavelength of light, although several research groups are now trying to go beyond this limit with the use of techniques from plasmonics or metamaterials. In this contribution, we present a subwavelength thin waveguide geometry that allows for guided waves with extremely good confinement properties. This waveguide makes use of a left-handed material, i.e., a material with negative index of refraction, in order to control the phase evolution of the optical mode during propagation.
First, we show that a left-handed material can be added to the cladding of an optical waveguide in order to tailor the phase shifts due to total internal reflection. We then calculate the dispersion relation for guided modes and we show that the proposed geometry allows for waveguides with a thickness that is at least one order of magnitude smaller than the wavelength. Contrary to traditional optical waveguides, this does not inversely affect the degree of confinement, i.e., the energy of the guided mode remains extremely well confined to the (subwavelength thin) core of the waveguide.