Laser-processed diffractive lenses for the frequency range of 47  THz

Indrišiūnas, Simonas; Richter, Heiko; Grigelionis, I.; Janonis, Vytautas; Minkevičius, Linas; Valušis, Gintaras; Račiukaitis, Gediminas; Hagelschuer, Till; Hübers, Heinz‐Wilhelm; Kašalynas, Irmantas

doi:10.1364/ol.44.001210

Cited by 16 publications

(15 citation statements)

References 14 publications

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“…The THz performance of the samples was investigated in the transmission mode in the frequency range from 0.1 to 4.7 THz using THz imaging and THz time-domain spectroscopy (THz TDS) systems described elsewhere [6], [9], [11]. A stylus profiler (Veeco Dektak 150) and a scanning electron microscope (SEM) (JEOL JSM) were used to characterize the morphology of the samples.…”

Section: Resultsmentioning

confidence: 99%

“…However, a few of them were processed in an argon (Ar) atmosphere at a pressure of 1 or 2 atm. The samples were fabricated from a 500 ± 25 μm thick, both-sides polished, (100) crystal orientation highresistivity float zone silicon wafer that was similar to the ones used elsewhere [9], [12].…”

Section: Samples and Experimental Setupmentioning

confidence: 99%

“…Off-axis parabolic mirrors and refractive lenses are available commercially and very often are employed in THz imaging setups. Compact diffractive lenses such as multilevel phase Fresnel lenses (MPFLs) and Fibonacci lenses have been developed on high-resistivity silicon (HR-Si) in order to reduce the complexity of the THz systems [6]- [9]. The advantages of diffractive optics have been experimentally confirmed by demonstrating almost diffraction-limited imaging results [10], [11].…”

Section: Introductionmentioning

confidence: 99%

“…However, in microstructuring applications in the efficient ablation regime, the spot size would be too large to obtain fine structural features. For example, fabrication of high-frequency MPFLs may require a spot size of 20 μm in diameter or even smaller [6], [9]. Therefore, it may be beneficial to exceed the optimal fluence.…”

Section: Introductionmentioning

confidence: 99%

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Laser-Ablated Silicon in the Frequency Range From 0.1 to 4.7 THz

Indrišiūnas

Svirplys

Richter

et al. 2019

IEEE Trans. THz Sci. Technol.

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The optical performance of high-resistivity silicon with a laser-ablated surface was studied in the transmission mode in the frequency range of 0.1-4.7 THz. A reciprocal relationship between the transmission brightness and the surface roughness was observed at discrete THz frequencies. The measured dispersion was reproduced by the THz wave scattering theory using an effective refractive index model. No significant differences between the samples processed either with ps-or ns-duration laser pulses in ambient air or in argon enriched atmosphere were found in the THz regime. It was demonstrated that the majority of optical losses of the silicon with the laser modified surface were due to the scattering of THz waves and not due to the absorption in silicon-compounds formed during the laser ablation.

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Section: Resultsmentioning

confidence: 99%

Section: Samples and Experimental Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Laser-Ablated Silicon in the Frequency Range From 0.1 to 4.7 THz

Indrišiūnas

Svirplys

Richter

et al. 2019

IEEE Trans. THz Sci. Technol.

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“…Moreover, the aspect ratio (height over width) of printed details is too big for proper manufacturing. Struggling with technology to obtain a higher resolution leads to more cost demanding solutions like etching [47] or ablation [48,49]. However, the material also changes-mostly for silicon.…”

Section: Figurementioning

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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Light Engineering and Silicon Diffractive Optics Assisted Nonparaxial Terahertz Imaging

Orlov,

Ivaškevičiūtė‐Povilauskienė,

Mundrys

et al. 2024

Laser & Photonics Reviews

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The art of light engineering unveils a world of possibilities through the meticulous manipulation of photonic properties such as intensity, phase, and polarization. Precision control over these properties finds application in a variety of fields spanning communications, light–matter interactions, laser direct writing, and imaging. Terahertz (THz) range, nestled between microwaves and infrared light, stands out for its remarkable ability to propagate with minimal losses in numerous dielectric materials and compounds, making THz imaging a powerful tool for noninvasive control and inspection. In this study, a rational framework for the design and optimal assembly of nonparaxial THz imaging systems is established. The research is centered on lensless photonic systems composed solely of high‐resistivity silicon‐based nonparaxial elements such as the Fresnel zone plate, the Fibonacci lens, the Bessel axicon, and the Airy zone plate, all fabricated using laser ablation technology. Through a comprehensive examination through illumination engineering and scattered light collection from raster‐scanned samples in a single‐pixel detector scheme, the imaging systems are evaluated via diverse metrics including contrast, resolution, depth of field, and focus. These findings chart an exciting course toward the development of compact and user‐friendly THz imaging systems where sensors and optical elements seamlessly integrate into a single chip.

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Laser-processed diffractive lenses for the frequency range of 47 THz

Cited by 16 publications

References 14 publications

Laser-Ablated Silicon in the Frequency Range From 0.1 to 4.7 THz

Laser-Ablated Silicon in the Frequency Range From 0.1 to 4.7 THz

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

Light Engineering and Silicon Diffractive Optics Assisted Nonparaxial Terahertz Imaging

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