Light confinement via periodic modulation of the refractive index

We investigate, both theoretically and numerically, light confine- ment in dielectric structures with a transverse refractive index distribution pe- riodically modulated in the longitudinal coordinate. We demonstrate that light can be guided even in the balanced limit when the average refractive index con- trast vanishes in the direction of propagation, a dynamic trapping phenomenon analogous to the Kapitza effect in quantum mechanics. Finally, with reference to segmented waveguides with an unbalanced index modulation, we address the interplay of dynamic and static confinements.