,Generation of wavelength-independent subwavelength Bessel beams using metasurfaces

• 作 者: Wei Ting Chen Mohammadreza Khorasaninejad Alexander Y.Zhu Jaewon Oh Robert C.Devlin Aun Zaidi Federico Capasso
• 机 构: Harvard John A.Paulson School of Engineering and Applied Sciences,Harvard University,Cambridge,MA 02
• 出 处: 光：科学与应用（英文版）
• 发表日期: 2017年2期
• 关键词: Bessel beam high numerical aperture light angular momentum metasurface

Bessel beams are of great interest due to their unique non-diffractive properties.Using a conical prism or an objective paired with an annular aperture are two typical approaches for generating zeroth-order Bessel beams.However,the former approach has a limited numerical aperture (NA),and the latter suffers from low efficiency,as most of the incident light is blocked by the aperture.Furthermore,an additional phase-modulating element is needed to generate higher-order Bessel beams,which in tu adds complexity and bulkiness to the system.We overcome these problems using dielectric metasurfaces to realize meta-axicons with additional functionalities not achievable with conventional means.We demonstrate meta-axicons with high NA up to 0.9 capable of generating Bessel beams with full width at half maximum about as small as ～M3 (λ=405 nm).Importantly,these Bessel beams have transverse intensity profiles independent of wavelength across the visible spectrum.These meta-axicons can enable advanced research and applications related to Bessel beams,such as laser fabrication,imaging and optical manipulation.