  A recent computational result suggests that highly confined modes can be
realized by all-dielectric metamaterials (S. Jahani et. al., Optica 1, 96
(2014)). This substantially decreases crosstalk between dielectric waveguides,
paving the way for high-density photonic circuits. Here, we experimentally
demonstrate, on a standard silicon-on-insulator (SOI) platform, that using a
simple metamaterial between two silicon strip waveguides results in about a
10-fold increase in coupling length. The proposed structure may lead to
significant reduction in the size of devices in silicon photonics.
