THz diffractive focusing structures for broadband application

Liebert, K.; Rachon, M.; Bomba, Jarosław; Sobczyk, Artur; Zagrajek, Przemysław; Sypek, Maciej; Suszek, Jarosław; Siemion, Agnieszka

doi:10.4302/plp.v10i3.845

Cited by 2 publications

(2 citation statements)

References 15 publications

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“…It is an interesting idea to use diffractive structures with extended depth of focus as optical elements focusing at a particular distance the radiation with a broader spectral range and maintaining small thickness [ 84 , 85 ]. However, in recent years, a vast majority of optical elements working broadband have been designed using metamaterials [ 76 , 86 , 87 ].…”

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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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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“…These structures are: the spherical focusing lens, the multi-focal lens, the axicon and the light sword optical element. The preliminary results describing focusing properties of spherical lenses, axicons and light sword elements were already presented [14].…”

Section: Introductionmentioning

confidence: 99%

Study of thin, achromatic diffractive structures to focus terahertz radiation on a detector

Liebert¹,

Rachon²,

Kołodziejczyk³

et al. 2020

Optica Applicata

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Thin and lightweight achromatic focusing elements with F-number close to 1 are desirable in many practical applications. We present the idea to use diffractive structures designed to work for the substantially increased THz frequency range. The paper analyses mono- and multi-focal lenses forming point-like foci as well as axicon and light sword optical elements focusing THz radiation into line segments located along the optical axis. We consider diffractive elements in a form of the first and the second order kinoforms having various thicknesses. Designed and fabricated elements were numerically and experimentally examined to verify their achromatic functioning. We present point spread functions (XY scans) and 2D energy maps (XZ scans) for different THz frequencies. Moreover, a diagram of chromatic aberration is created by registering energy distribution along the optical axis for different frequencies. The distance corresponding to the highest energy is chosen for each frequency. Therefore, we can compare broadband working of designed structures. The spherical lens coded as kinoform of the second order provides the best broadband functioning, however it is two times thicker than structures providing extended depth of focus (light sword and axicon) working with slightly smaller efficiency but being much thinner.

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THz diffractive focusing structures for broadband application

Cited by 2 publications

References 15 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

Study of thin, achromatic diffractive structures to focus terahertz radiation on a detector

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