Generation of wavelength-independent subwavelength Bessel beams using metasurfaces

• 来源期刊: 光：科学与应用（英文版）
• 关键词: Bessel beam high numerical aperture light angular momentum metasurface
• 年，卷（期）: 2017,（2）
• 页码范围: 167-172
• 页数: 6页
• 语种: 英文
• DOI: 10.1038/lsa.2016.259

摘要

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 turn 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.