First on-chip metamaterial with zero refractive index is promising for manipulating light in PICs

The first on-chip metamaterial with a refractive index of 0 gives light an infinite phase velocity, which could be advantageous for manipulating light in photonic integrated circuits.

The metamaterial consists of silicon pillar arrays embedded in a polymer matrix and clad in gold film and was developed at Harvard University’s John A. Paulson School of Engineering and Applied Sciences. It can couple to silicon waveguides to interface with standard integrated photonic components and chips.

“Integrated photonic circuits are hampered by weak and inefficient optical energy confinement in standard silicon waveguides,” said postdoctoral fellow Yang Li. “This zero-index metamaterial offers a solution for the confinement of electromagnetic energy in different waveguide configurations because its high internal phase velocity produces full transmission, regardless of how the material is configured.”

Silicon pillar arrays In this zero-index material — made of silicon pillar arrays embedded in a polymer matrix and clad in gold film — light experiences no phase advance. Courtesy of Peter Allen/Harvard SEAS.
Light’s phase velocity increases or decreases as a function of the refractive index of the material it’s moving through. Phase velocity slows down, for example, when a light wave moves from air into water, and speeds up again when it re-enters the air. Air’s refractive index is 1, and water’s is about 1.3.Read more


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