Light confinement via periodic modulation of the refractive index

We investigate, both theoretically and numerically, light confinement in dielectric structures with a transverse refractive index distribution periodically modulated in the longitudinal coordinate. We demonstrate that light can be guided even in the balanced limit when the average refractive index contrast 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.