We propose and study a box-shaped waveguide based on Si3N4 which confines the light in a sub-wavelength region. The mode characteristics of the proposed structure have been investigated thoroughly.
Radiation coupling plays a key role in the bending waveguide structure with very small bending radius. Insights of radiation coupling and energy transfer by way of high order bending modes have been discussed. Modes in bending waveguide structures with small bending radii are investigated.