Polarization conversion efficiency is vitally important to highly efficient wavefront manipulation based on phase discontinuities. However, previous single-layer phase gradient metasurfaces have suffered from low polarization conversion efficiency (at most 25%). Here we present a three-layer structure to enhance polarization conversion efficiency. The average efficiency is 76% for circularly polarized incident light converted to its opposite handedness. By arraying metallic antennas with varied optical axes for circularly polarized incident light, the efficiency of anomalous refraction is apparently increased, and the focused intensity of flat lenses can be significantly enhanced in the terahertz regime. It is expected that this scheme has potential applications in detection, focusing, and imaging.
© 2014 Optical Society of America
Original Manuscript: January 13, 2014
Revised Manuscript: March 9, 2014
Manuscript Accepted: March 10, 2014
Published: April 3, 2014
Jun Luo, Honglin Yu, Maowen Song, and Zuojun Zhang, "Highly efficient wavefront manipulation in terahertz based on plasmonic gradient metasurfaces," Opt. Lett. 39, 2229-2231 (2014)