Structured light-electromagnetic waves with a strong spatial inhomogeneity of amplitude,phase,and polarization-has occupied far-reaching positions in both optical research and applications.Terahertz(THz)waves,due to recent innovations in photonics and nanotechnology,became so robust that it was not only implemented in a wide variety of applications such as communications,spectroscopic analysis,and non-destructive imaging,but also served as a low-cost and easily implementable experimental platform for novel concept illustration.In this work,we show that structured nonparaxial THz light in the form of Airy,Bessel,and Gaussian beams can be generated in a compact way using exclusively silicon diffractive optics prepared by femtosecond laser ablation technology.The accelerating nature of the generated structured light is demonstrated via THz imaging of objects partially obscured by an opaque beam block.Unlike conventional paraxial approaches,when a combination of a lens and a cubic phase(or amplitude)mask creates a nondiffracting Airy beam,we demonstrate simultaneous lensless nonparaxial THz Airy beam generation and its application in imaging system.Images of single objects,imaging with a controllable placed obstacle,and imaging of stacked graphene layers are presented,revealing hence potential of the approach to inspect quality of 2D materials.Structured nonparaxial THz illumination is investigated both theoretically and experimentally with appropriate extensive benchmarks.The structured THz illumination consistently outperforms the conventional one in resolution and contrast,thus opening new frontiers of structured light applications in imaging and inverse scattering problems,as it enables sophisticated estimates of optical properties of the investigated structures.

Rusnè lva?kevi?iūtè-Povilauskienè;Paulius Kizevi?ius;Ernestas Nacius;Domas Jokubauskis;K?stutis lkamas;Alvydas Lisauskas;Natalia Alexeeva;leva Matulaitienè;Vytautas Jukna;Sergej Orlov;Linas Minkevi?ius;Gintaras Valu?is

Department of Optoelectronics,Center for Physical Sciences and Technology,Sauletekio av.3,Vilnius 10257,Lithuania;Department of Fundamental Research,Center for Physical Sciences and Technology,Saulètekio av.3,Vilnius 10257,Lithuania;Institute of Applied Electrodynamics&Telecommunications,Vilnius University,Saulètekio av.3,Vilnius 10257,Lithuania;CENTERA Labs.,Institute of High Pressure Physics PAS,ul.Sokolowska 29/37,Warsaw 01-142,Poland;Department of Organic Chemistry,Center for Physical Sciences and Technology,Saulètekio av.3,Vilnius 10257,Lithuania;Institute of Photonics and Nanotechnology,Department of Physics,Vilnius University,Saulètekio av.3,Vilnius 10257,Lithuania

光：科学与应用（英文版）

[1]Rusnè lva?kevi?iūtè-Povilauskienè;Paulius Kizevi?ius;Ernestas Nacius;Domas Jokubauskis;K?stutis lkamas;Alvydas Lisauskas;Natalia Alexeeva;leva Matulaitienè;Vytautas Jukna;Sergej Orlov;Linas Minkevi?ius;Gintaras Valu?is-.Terahertz structured light:nonparaxial Airy imaging using silicon diffractive optics)[J].光：科学与应用（英文版）,2022(12):2909-2921

nonparaxial,nondiffracting

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