High‐Efficiency Synthesizer for Spatial Waves Based on Space‐Time‐Coding Digital Metasurface. Issue 6 (11th May 2020)

• Record Type: Journal Article
• Authors: Dai, Jun Yan; Yang, Liu Xi; Ke, Jun Chen; Chen, Ming Zheng; Tang, Wankai; Li, Xiang; Chen, Mao; Wu, Zhan Hao; Cheng, Qiang; Jin, Shi; Cui, Tie Jun
• Is Part Of: Laser & photonics reviews. Volume 14:Issue 6(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-05-11
• Subjects: high‐efficiency nonlinear harmonic conversion -- space‐time‐coding digital metasurface -- spatial wave synthesis; Lasers -- Periodicals; Photonics -- Periodicals; Lasers -- Périodiques; Photonique -- Périodiques; 621.36
• DOI: 10.1002/lpor.201900133
• Languages: English
• ISSNs: 1863-8880

Abstract

Abstract: Space‐time modulated metasurfaces enable efficient manipulations of nonlinear harmonics with more degrees of freedom than conventional materials by simply controlling the element geometries and modulation signals. The theoretical analyses reveal that a group of harmonics in reflected waves could be generated by the metasurface under the incidence of monochromatic wave with the rapid change of surface reflectivity, while the fundamental spectrum is greatly suppressed. However, it remains a great challenge to synthesize a high‐quality single‐tone signal for the reflected waves with excellent rejection ratio for higher‐order harmonics, which is highly desired for applications like wireless communications and radar detection. Here, a new scheme to overcome this limit, which experimentally realizes high‐efficiency frequency conversion from the fundamental harmonic to the + 1 s t / − 1 s t order harmonic of reflected waves, and beam shaping based on the space‐time joint coding strategy are proposed. The measured results show that the maximum conversion efficiency is greater than 88%. This design can also find widespread applications in THz frequencies when the active metasurface for periodical phase modulations is further developed. Abstract : A new design of space‐time‐coding digital metasurface for high‐efficiency spatial synthesis is proposed in this article. By employing linear phase modulation to the metasurface, both frequency conversion and beam shaping are implemented simultaneously with the maximum conversion efficiency of 88.81% and largest harmonic suppression ratio of 21.03 dB. The presented work is promising for the next‐generation wireless communication and radar systems.