Low-Loss Zero-Index Materials

Materials with a zero refractive index support electromagnetic modes that exhibit stationary phase profiles. While such materials have been realized across the visible and near-infrared spectral range, radiative dissipative optical losses hindered their development. We reduce in zero-index, on-chip photonic crystals by introducing high-Q resonances via resonance-trapped symmetry-protected states. Using these approaches, we experimentally obtain quality factors of 2.6 × 103 7.8 at wavelengths, corresponding to an order-of-magnitude reduction propagation loss over previous designs. Our work presents viable approach fabricate zero-index nanophotonic devices low-loss.