Broadband and high-efficiency accelerating beam generation by dielectric catenary metasurfaces

Fei Zhang,Yinghui Guo,Mingbo Pu,Xiangang Luo,Xiaoliang Ma,Qingyu Zeng,Xiong Li,Yanqin Wang

doi:10.1515/nanoph-2020-0057

Abstract

Abstract Self-accelerating beams show considerable captivating phenomena and applications owing to their transverse acceleration, diffraction-free and self-healing properties in free space. Metasurfaces consisting of dielectric or metallic subwavelength structures attract enormous attention to acquire self-accelerating beams, owing to their extraordinary capabilities in the arbitrary control of electromagnetic waves. However, because the self-accelerating beam generator possesses a large phase gradient, traditional discrete metasurfaces suffer from insufficient phase sampling, leading to a low efficiency and narrow spectral band. To overcome this limitation, a versatile platform of catenary-inspired dielectric metasurfaces is proposed to endow arbitrary continuous wavefronts. A high diffraction efficiency approaching 100% is obtained in a wide spectral range from 9 to 13 μm. As a proof-of-concept demonstration, the broadband, high-efficiency and high-quality self-accelerating beam generation is experimentally verified in the infrared band. Furthermore, the chiral response of the proposed metasurfaces enables the spin-controlled beam acceleration. Considering these superior performances, this design methodology may find wide applications in particle manipulation, high-resolution imaging, optical vortex generation, and so forth.

Highlights

In recent decades, diffraction-free waves have attracted enormous attentions [1, 2]
Self-accelerating beams show considerable captivating phenomena and applications owing to their transverse acceleration, diffraction-free and self-healing properties in free space
As a sort of special dispersionfree beams, Airy beams [3] or, more generally, self-accelerating beams [4, 5] bear self-healing properties and possess a unique transverse acceleration characteristic since their main peaks propagate along a nonlinear curve

Summary

Introduction

Diffraction-free waves have attracted enormous attentions [1, 2]. Self-accelerating beams have considerable applications in various fields, such as filamentation [6], imaging [7], light bullet [8], and optical manipulation [9]. There have been abundant investigations on the generation of self-accelerating beams [10, 11]. Traditional methods usually acquire self-accelerating beams in the Fourier domain by encoding a cubic-phase distribution in liquid crystal spatial light modulators [12, 13] or adaptive deformable mirrors [14]. The applications of self-accelerating beams in the compact nanophotonic platform are mainly hindered by both those hulking elements and the extraordinary long working distance of the Fourier Transform system

Methods

Results

Conclusion