Generation of a terahertz collimated top-hat beam by using two thin diffractive phase plates

Yang, Xi; Xiang, Feidi; You, Chengwu; Wang, Kejia; Yang, Zhengang; Liu, Jinsong; Wang, Shenglie

doi:10.1364/osac.1.001341

Cited by 14 publications

(3 citation statements)

References 18 publications

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“…Such a setup allows creating the image only by shifting the sample but gives the opportunity to suppress negative diffraction effects. The necessity of forming uniform illumination was noticed [ 66 ] which resulted in forming top-hat beam with two refractive or two diffractive structures. The experimental evaluation clearly indicated a better and more uniform beam while using diffractive elements.…”

Section: Features Of Thz Designmentioning

confidence: 99%

The Magic of Optics—An Overview of Recent Advanced Terahertz Diffractive Optical Elements

Siemion

2020

Sensors

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Diffractive optical elements are well known for being not only flat but also lightweight, and are characterised by low attenuation. In different spectral ranges, they provide better efficiency than commonly used refractive lenses. An overview of the recently invented terahertz optical structures based on diffraction design is presented. The basic concepts of structure design together with various functioning of such elements are described. The methods for structure optimization are analysed and the new approach of using neural network is shown. The paper illustrates the variety of structures created by diffractive design and highlights optimization methods. Each structure has a particular complex transmittance that corresponds to the designed phase map. This precise control over the incident radiation phase changes is limited to the design wavelength. However, there are many ways to overcome this inconvenience allowing for broadband functioning.

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Section: Features Of Thz Designmentioning

confidence: 99%

The Magic of Optics—An Overview of Recent Advanced Terahertz Diffractive Optical Elements

Siemion

2020

Sensors

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“…The range of passive approaches is much more extensive. Uniform illumination can be obtained by applying optimized refractive/reflective optical setups and elements 1 , 8 , 9 (including freeform optics), lenslet arrays 2 or diffractive optical structures 10 . This work focuses on a diffractive approach.…”

Section: Introductionmentioning

confidence: 99%

Segmentation of THz holograms for homogenous illumination

Surma,

Kaluza,

Komorowski

et al. 2024

Sci Rep

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This paper investigates the feasibility of applying the hologram segmentation method for homogeneous illumination. Research focuses on improving the uniformity of the illumination obtained from diffractive optical elements in the THz range. The structures are designed with a modified Ping-Pong algorithm and a neural network-based solution. This method allows for the improvement of uniform illumination distribution with the desired shape. Additionally, the phase modulations of the structures are divided into segments, each responsible for imaging at different distances. Various segment combination methods are investigated, differing in shapes, image plane distances, and illumination types. The obtained image intensity maps allow for the identification of the performance of each combination method. Each of the presented structures shows significant improvements in the uniformity of imaged targets compared to the reference Ping-Pong structure. The presented structures were designed for a narrow band case—260 GHz frequency, which corresponds to 1.15 mm wavelength. The application of diffractive structures for homogenization of illumination shows promise. The created structures perform designed beamforming task with variability of intensity improved up to 23% (standard deviation) or 45% (interquartile range) compared with reference structure.

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“…35 Previously, Top-Hat beams were generated using diffractive optical elements among others, which shape the beam to high-order super-Gaussian profiles. 36,37 In the present study, the near-field amplitude was structurally matched to E THz = sinc(a•x), where a = 2 mm −1 , resulting in the conversion of the emission into a Top-Hat beam with a uniform intensity profile in the far-field. The design parameters of the sample are presented in Figure 4a, illustrating the required precision to generate the sinc kernel function.…”

mentioning

confidence: 98%

Holographic THz Beam Generation by Nonlinear Plasmonic Metasurface Emitters

Sideris,

Zixian,

McDonnell

et al. 2023

ACS Photonics

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The advancement of terahertz (THz) technology hinges on the progress made in the development of efficient sources capable of generating and shaping the THz emission. However, the currently available THz sources provide limited control over the generated field. Here, we use near-field interactions in nonlinear Pancharatnam−Berry phase plasmonic metasurfaces to achieve deep subwavelength, precise, and continuous control over the local amplitude of the emitted field. We show that this new ability can be used for holographic THz beam generation. Specifically, we demonstrate the generation of precisely shaped Hermite− Gauss, Top−Hat, and triangular beams. We show that using this method, higher-order modes are completely suppressed, indicating optimal nonlinear diffraction efficiency. In addition, we demonstrate the application of the generated structured beams for obtaining enhanced imaging resolution and contrast. These demonstrations hold immense potential to address challenges associated with a broad range of new applications employing THz technology.

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Generation of a terahertz collimated top-hat beam by using two thin diffractive phase plates

Cited by 14 publications

References 18 publications

The Magic of Optics—An Overview of Recent Advanced Terahertz Diffractive Optical Elements

The Magic of Optics—An Overview of Recent Advanced Terahertz Diffractive Optical Elements

Segmentation of THz holograms for homogenous illumination

Holographic THz Beam Generation by Nonlinear Plasmonic Metasurface Emitters

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