Fibonacci terahertz imaging by silicon diffractive optics

Jokubauskis, Domas; Minkevičius, Linas; Karaliūnas, Mindaugas; Indrišiūnas, Simonas; Kašalynas, Irmantas; Račiukaitis, Gediminas; Valušis, Gintaras

doi:10.1364/ol.43.002795

Cited by 29 publications

(16 citation statements)

References 22 publications

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“…To reduce the losses, high-density polyethylene (HDPE) materials or polyamide layers can be replace by high-resistivity silicon-based multilevel phase Fresnel lenses [211] or zone plates (Figure 4) fabricated, for instance, by laser ablation technology [212]. It was shown that such components can successfully be used for THz beam focusing, as well as beam-engineering, for instance, in Bessel or Fibonacci-beam generation [213,214]. The approach works well even for large apertures, up to 50 mm [215], and it allows for reaching nearly 90% transmittance of silicon antireflection layers and produce focusing by binary zone plates [216].…”

Section: Diffractive Optical Components and Beamforming (Beam Engineering) In Thz Imagingmentioning

confidence: 99%

Roadmap of Terahertz Imaging 2021

Valušis

Lisauskas

Yuan

et al. 2021

Sensors

175

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In this roadmap article, we have focused on the most recent advances in terahertz (THz) imaging with particular attention paid to the optimization and miniaturization of the THz imaging systems. Such systems entail enhanced functionality, reduced power consumption, and increased convenience, thus being geared toward the implementation of THz imaging systems in real operational conditions. The article will touch upon the advanced solid-state-based THz imaging systems, including room temperature THz sensors and arrays, as well as their on-chip integration with diffractive THz optical components. We will cover the current-state of compact room temperature THz emission sources, both optolectronic and electrically driven; particular emphasis is attributed to the beam-forming role in THz imaging, THz holography and spatial filtering, THz nano-imaging, and computational imaging. A number of advanced THz techniques, such as light-field THz imaging, homodyne spectroscopy, and phase sensitive spectrometry, THz modulated continuous wave imaging, room temperature THz frequency combs, and passive THz imaging, as well as the use of artificial intelligence in THz data processing and optics development, will be reviewed. This roadmap presents a structured snapshot of current advances in THz imaging as of 2021 and provides an opinion on contemporary scientific and technological challenges in this field, as well as extrapolations of possible further evolution in THz imaging.

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Section: Diffractive Optical Components and Beamforming (Beam Engineering) In Thz Imagingmentioning

confidence: 99%

Roadmap of Terahertz Imaging 2021

Valušis

Lisauskas

Yuan

et al. 2021

Sensors

175

View full text Add to dashboard Cite

show abstract

“…Focusing of the radiation does not have to be limited to a single focal spot but can also be understood as forming multiple focal spots (one after another), creating focal curves of different shapes or functioning for a broader range of frequencies. The Fibonacci lens design [79,80] was used to form bifocal diffractive lenses realized as binary structures with zone widths and position calculated according to the golden ratio [81]. Such elements were used to point-to-point imaging of volume objects-two planes corresponding to two focal lengths were imaged simultaneously forming an image with wavelength resolution.…”

Section: Efficient Focusing Of Thz Radiationmentioning

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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“…To obtain better performance of focusing, the typical design of the Fresnel zone plate can be substituted by fractal and Fibonacci lens-like structures [94]. The Fibonacci structure has been used for bifocal imaging which enables obtaining better resolution [95]. Additionally, DOEs can focus the incident wavefront into different shapes of focal curves [96,97]-like segments shorter and longer than the size of the structure, rings, lines, and matrix of points [98,99].…”

Section: Advanced Diffractive Optical Elementsmentioning

confidence: 99%

Terahertz Diffractive Optics—Smart Control over Radiation

Siemion

2019

J Infrared Milli Terahz Waves

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Over the last 20 years, thin and lightweight optical elements have become very desirable, especially for the terahertz (THz) range. Reduction of the volume of optical elements alongside an increase in their effective efficiency has begun a new direction of research leading to many practical applications. On top of that, diffractive optical elements can not only focus the incident beam, but also can shape the incoming wavefront into a desirable distribution or can redirect the energy. Starting from theoretical calculations of Fourier optics, diffractive elements have been transformed and nowadays form complicated structures that do not resemble a typical Fresnel lens. The precise control over a phase shift introduced by the designed element creates an opportunity to almost freely transform an incident wavefront. Moreover, the vast diversity of computer-generated holograms (also called synthetic) contributes substantially to this topic. Diffractive elements have a great impact on THz optical systems because their manufacturing is very simple in comparison with any other range of radiation (infrared, visible, ultraviolet, etc.). This review paper underlines developments in evolution of diffractive optics and highlights main principles and technological approaches for fabrication of diffraction optics within the terahertz range, thus serving as a guide to design and production considerations.

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Fibonacci terahertz imaging by silicon diffractive optics

Cited by 29 publications

References 22 publications

Roadmap of Terahertz Imaging 2021

Roadmap of Terahertz Imaging 2021

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

Terahertz Diffractive Optics—Smart Control over Radiation

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