The zero index metamaterials (ZIM) have been an intense research topic in nanophotonics. In ZIMs, the effective wavelength becomes infinite, and the spatial phase distribution of the propagating wave becomes uniform in the medium, overcoming many limitations imposed by the short spatial wavelength in the optical regime. This feature of ZIMs leads to applications including on-chip super coupling, nonlinear pumping, and on-chip orbital angular momentum generation. However, the traditional methods to realize ZIM face Ohm loss or out-of-plane radiation. In this work, we propose Steiner tree networks featuring a Dirac-like point and a photonic stop gap to realize low-loss 3D ZIM.
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