Laser precession machining of cross-shaped terahertz bandpass filters

Le, Hoang; Pradhani, Chandrasekhar; Penchev, Pavel; Nasrollahi, Vahid; Karkantonis, Themistoklis; Wang, Yi; Dimov, Stefan Simeonov; Ramos-de-Campos, José A.

doi:10.1016/j.optlaseng.2021.106790

Cited by 3 publications

(1 citation statement)

References 42 publications

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“…The same method was used to ablate cross-patterns combined into the Fresnel zone plate for THz focusing at specific wavelengths [ 6 ], which was also demonstrated by patterning of graphite on flexible substrates [ 7 ]. Using sub-0.5 ps pulses at ∼

m wavelength focused by a telecentric lens under galvanometric scanning, a superior shape control of the side wall angle (with the surface normal) can be achieved [ 8 ]. This is important for high-volume manufacturing, as well as for gaining control of the surface the roughness, which reduces conductivity

due to roughness factor

, where

is for smooth surface, affecting filter performance at lower frequency ∼

THz window [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

THz Filters Made by Laser Ablation of Stainless Steel and Kapton Film

Han

Smith

et al. 2022

Micromachines

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THz band-pass filters were fabricated by femtosecond-laser ablation of 25-μm-thick micro-foils of stainless steel and Kapton film, which were subsequently metal coated with a ∼70 nm film, closely matching the skin depth at the used THz spectral window. Their spectral performance was tested in transmission and reflection modes at the Australian Synchrotron’s THz beamline. A 25-μm-thick Kapton film performed as a Fabry–Pérot etalon with a free spectral range (FSR) of 119 cm−1, high finesse Fc≈17, and was tuneable over ∼10μm (at ∼5 THz band) with β=30∘ tilt. The structure of the THz beam focal region as extracted by the first mirror (slit) showed a complex dependence of polarisation, wavelength and position across the beam. This is important for polarisation-sensitive measurements (in both transmission and reflection) and requires normalisation at each orientation of linear polarisation.

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due to roughness factor

, where

is for smooth surface, affecting filter performance at lower frequency ∼

THz window [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

THz Filters Made by Laser Ablation of Stainless Steel and Kapton Film

Han

Smith

et al. 2022

Micromachines

View full text Add to dashboard Cite

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Resonant Terahertz Field-effect Transistors for Spectroscopic Sensing Applications

Kocybik

Krysl

Vieweg

et al. 2022

2022 47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)

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Investigation of precession laser machining of microholes in aerospace material

Nasrollahi

Karkantonis

et al. 2023

Journal of Laser Applications

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Sidewall tapering is one of the main limitations in ultrashort pulse (USP) laser machining and is associated with the beam shape and self-limiting effect. Laser processing with a precession beam is a potential solution to overcome this limitation. A study into the effects of precession parameters on the taper angle in microhole drilling of a nickel alloy is reported in this paper. The effects of three key precession parameters, i.e., incident angle, relative distance between the focuses of the precession and individual beams, and scanning speed, have been investigated in detail. Experiments were performed to drill through holes with aspect ratios up to 20:1 and diameters ranging from 100 to 500 μm over 0.6–2 mm thick nickel alloy substrates. Experiment results showed that all the considered parameters/factors were significant and affected the hole tapering in different ways. In addition, there were important interaction effects between two of the factors, i.e., incident angle and focus position, in some cases. The optimal parameters to minimize the tapering effect are suggested, and the mechanism is discussed in detail. The precession laser machining showed clear advantages in overcoming the limitations to associated with conventional USP laser machining. Fabricating microholes with high geometrical accuracy, i.e., with straight side walls and zero taper angles, is feasible with the use of a precession beam. The results clearly show the potential of precession laser processing and the capabilities that the technology can offer for a range of laser micromachining applications in different industries, such as microelectronics, automotive, and aerospace.

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Laser precession machining of cross-shaped terahertz bandpass filters

Cited by 3 publications

References 42 publications

THz Filters Made by Laser Ablation of Stainless Steel and Kapton Film

THz Filters Made by Laser Ablation of Stainless Steel and Kapton Film

Resonant Terahertz Field-effect Transistors for Spectroscopic Sensing Applications

Investigation of precession laser machining of microholes in aerospace material

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