原子厚度的二维亚波长超透镜

Subwavelength Optical Lenses Based on 2D Materials

超透镜(Metalens)是结合了超表面原理和超薄平板光学原理制作的一类自身尺度在亚波长范围内,能够对光波前进行重塑的新兴人工光学器件。二维范德华材料的出现为超透镜光学器件提供了丰富的材料选择以及功能调控方面的可能。以石墨烯、过渡族金属硫族化合物等为典型代表的二维材料归功于其层间相对较弱的范德华相互作用,可通过机械剥离、化学气相沉积等方法获得原子层厚度平整的单晶,天然满足超透镜材料厚度尺寸要求,其自身以及溶于溶剂形成的二维液晶材料均具有优异的电学、光学、机械、磁性等丰富的物理特性,且性能高度可调控,使得基于二维材料的超透镜除能满足传统透镜的特性功能外,还有望通过包括静电调控等方式得到具有可调控的新奇物理特性。因此,对基于二维材料的超透镜的发展现状进行总结,并结合其材料结构特性进行相关的展望对该行业的发展是十分迫切的。本综述主要围绕二维材料超透镜展开,概述了该类透镜的研究进展,包括二维层状材料以及二维液晶材料、二维材料超透镜的潜在应用前景,以及对二维超透镜这一新兴研究领域未来的发展方向进行了适当的总结与展望。

With the discovery of graphene,a frenzy was set in motion to explore two-dimensional materials and its potential applications.In recent years,considerable efforts have been devoted to the demonstration of atomically-thin optical devices using graphene,transition metal dichalcogenides,and other two-dimensional(2D)materials.The combination of two-dimensional materials and flat-optics has yielded fruitful unexpected results.These ultra-thin two-dimensional optical devices can not only realize the functions of traditional diffractive lenses,but also show excellent optical modulability in the sub-wavelength range,which broadens the potential of future applications.In addition to the excellent physical properties(such as good ductility and flexible substrate compatibility)of 2D materials,their Fermi level can be further tuned by gate voltage,thus effectively modulating the optical properties without moving the optical components,which makes the 2D ultra-thin optical components superior in terms of tunability as compared to conventional devices.Besides,tunable liquid crystal lens has a mature development,and graphene oxide,transition metal disulfide and many other two-dimensional materials also possess stable liquid crystal phases.It is natual to pay attention to ultrathin liquid crystal lenses based on two-dimensional materials in order to achieve the flexible and responsive two-dimensional tunable lenses.The emergence of two-dimensional ultra-thin tunable optics has not only paved the development of the next generation of optics,but also provided new hope for further high integration of optical components.Therefore,this review focuses on ultrathin lenses made of two-dimensional materials,as it will briefly outline the recent progress of subwavelength optical lenses made of two-dimensional layered materials as well as two-dimensional liquid crystal 2D materials.Moreover,this review also introduces the potential application of such lenses,and gives an outlook of this emerging research field.