Guiding and confining light in void nanostructure

We present a novel waveguide geometry for enhancing and confining light in a nanometer-wide low-index material. Light enhancement and confinement is caused by large discontinuity of the electric field at high-index-contrast interfaces. We show that by use of such a structure the field can be confined in a 50-nm-wide low-index region with a normalized intensity of $20 \mathit{\mu }{\mathrm{m}}^{-2}$. This intensity is approximately 20 times higher than what can be achieved in ${\mathrm{SiO}}_2$ with conventional rectangular waveguides.