Observation of zeroth-order band gaps in negative-refraction photonic crystal superlattices at near-infrared frequencies.

We present the first observations of zero-n[over ] band gaps in photonic crystal superlattices consisting of alternating stacks of negative-index photonic crystals and positive-index dielectric materials in the near-infrared range. Guided by ab initio three-dimensional numerical simulations, the fabricated nanostructured superlattices demonstrate the presence of zeroth-order gaps in remarkable agreement with theoretical predictions across a range of different superlattice periods and unit cell variations. These volume-averaged zero-index superlattice structures present a new type of photonic band gap, with the potential for complete wave front control for arbitrary phase delay lines and open cavity resonances.