Affiliation:
1. University of Madras (Guindy Campus)
2. THz Technical Research Center of Shenzhen University
3. Indian Institute of Technology Madras
Abstract
Optical wavefront transformation is essential for communication and power transfer applications across all electromagnetic spectra. In this work, we report directional multi-beam compact wavefront transformers which convert cylindrical wavefronts into finite-aperture directional beams based on near-zero refraction in 3-D metamaterial at terahertz frequencies. For this purpose, a near-zero-index metamaterial (NZIM) with three-dimensional functionality is realized, and its effective material parameters are retrieved. Near-zero refraction in NZIM is verified through the uniform phase maintenance inside the multiple stacked NZIM layers. By embedding a cylindrical wavefront source inside NZIM configurations, uni-, bi-, and quad-directional wavefront transformers are realized. The results were compared and verified against the ideal cases.