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Kumagai K, Huang HH, Hatanaka K, Hayasaki Y. Computational broadband imaging with laser-driven sequential light source arrays on a water film. OPTICS EXPRESS 2023; 31:9554-9562. [PMID: 37157523 DOI: 10.1364/oe.483563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Imaging and computational processing fusion technologies have expanded the wavelength range that can be visualized. However, it is still challenging to realize a system that can image a wide range of wavelengths, including non-visible regions, in a single system. Here, we propose a broadband imaging system based on femtosecond-laser-driven sequential light source arrays. The light source arrays allow us to form ultra-broadband illumination light depending on the excitation target and irradiated pulse energy. We demonstrated X-ray and visible imaging under atmospheric pressure by using a water film as an excitation target. Furthermore, by applying a compressive sensing algorithm, the imaging time was reduced while maintaining the number of pixels in the reconstructed image.
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THz Filters Made by Laser Ablation of Stainless Steel and Kapton Film. MICROMACHINES 2022; 13:mi13081170. [PMID: 35893168 PMCID: PMC9330792 DOI: 10.3390/mi13081170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/18/2022] [Accepted: 07/19/2022] [Indexed: 11/17/2022]
Abstract
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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Giant Enhancement of THz Wave Emission under Double-Pulse Excitation of Thin Water Flow. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10062031] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Simultaneous measurements of THz wave and hard X-ray emission from thin and flat water flow when irradiated by double femtosecond laser pulses (800 nm, 35 fs/transform-limited, 0.5 kHz, delay times up to 15 ns) were carried out. THz wave measurements by time-domain spectroscopy and X-ray detection by Geiger counters were performed at the transmission and the reflection sides of the flow. THz wave emission spectra show their dynamic peak shifts toward the low frequency with the highest intensity enhancements more than 1.5 × 10 3 times in |E| 2 accumulated over the whole spectrum range of 0–3 THz at the delay time of 4.7 ns between the two pulses. On the other hand, X-ray intensity enhancements are limited to about 20 times at 0 ns under the same experimental conditions. The mechanisms for the spectral changes and the intensity enhancements in THz wave emission are discussed from the viewpoint of laser ablation on the water flow induced by the pre-pulse irradiation.
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Hsu WH, Masim FCP, Balčytis A, Huang HH, Yonezawa T, Kuchmizhak AA, Juodkazis S, Hatanaka K. Enhancement of X-ray emission from nanocolloidal gold suspensions under double-pulse excitation. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:2609-2617. [PMID: 30416911 PMCID: PMC6204784 DOI: 10.3762/bjnano.9.242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/09/2018] [Indexed: 06/09/2023]
Abstract
Enhancement of X-ray emission was observed from a micro-jet of a nano-colloidal gold suspension in air under double-pulse excitation of ultrashort (40 fs) near-IR laser pulses. Temporal and spatial overlaps between the pre-pulse and the main pulse were optimized for the highest X-ray emission. The maximum X-ray intensity was obtained at a 1-7 ns delay of the main pulse irradiation after the pre-pulse irradiation with the micro-jet position shifted along the laser beam propagation. It was revealed that the volume around gold nanoparticles where the permittivity is near zero, ε ≈ 0, accounts for the strongest absorption, which leads to the effective enhancements of X-ray emission.
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Affiliation(s)
- Wei-Hung Hsu
- Research Center for Applied Sciences, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | | | - Armandas Balčytis
- Centre for Micro-Photonics, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
| | - Hsin-Hui Huang
- Research Center for Applied Sciences, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Tetsu Yonezawa
- Division of Materials Science and Engineering, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 0608628, Japan
| | - Aleksandr A Kuchmizhak
- School of Natural Sciences, Far Eastern Federal University (FEFU), Vladivostok 690041, Russia
- Institute of Automation and Control Processes, Far Eastern Branch, Russian Academy of Science, Vladivostok 690041, Russia
| | - Saulius Juodkazis
- Centre for Micro-Photonics, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
- Melbourne Centre for Nanofabrication, the Victorian Node of the Australian National Fabrication Facility, Clayton 3168 VIC, Australia
| | - Koji Hatanaka
- Research Center for Applied Sciences, Academia Sinica, Nankang, Taipei 11529, Taiwan
- College of Engineering, Chang Gung University , Guishan, Taoyuan 33302, Taiwan
- Department of Materials Science and Engineering, National Dong-Hwa University, Shoufeng, Hualien 97401, Taiwan
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Huang HH, Nagashima T, Hsu WH, Juodkazis S, Hatanaka K. Dual THz Wave and X-ray Generation from a Water Film under Femtosecond Laser Excitation. NANOMATERIALS 2018; 8:nano8070523. [PMID: 30011794 PMCID: PMC6071190 DOI: 10.3390/nano8070523] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 07/10/2018] [Accepted: 07/11/2018] [Indexed: 11/16/2022]
Abstract
Simultaneous emission of the THz wave and hard X-ray from thin water free-flow was induced by the irradiation of tightly-focused femtosecond laser pulses (35 fs, 800 nm, 500 Hz) in air. Intensity measurements of the THz wave and X-ray were carried out at the same time with time-domain spectroscopy (TDS) based on electro-optic sampling with a ZnTe(110) crystal and a Geiger counter, respectively. Intensity profiles of the THz wave and X-ray emission as a function of the solution flow position along the incident laser axis at the laser focus show that the profile width of the THz wave is broader than that of the X-ray. Furthermore, the profiles of the THz wave measured in reflection and transmission directions show different features and indicate that THz wave emission is, under single-pulse excitation, induced mainly in laser-induced plasma on the water flow surface. Under double-pulse excitation with a time separation of 4.6 ns, 5–10 times enhancements of THz wave emission were observed. Such dual light sources can be used to characterise materials, as well as to reveal the sequence of material modifications under intense laser pulses.
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Affiliation(s)
- Hsin-Hui Huang
- Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan.
| | - Takeshi Nagashima
- Faculty of Science and Engineering, Setsunan University, 17-8 Ikeda-Nakamachi, Neyagawa, Osaka 572-8508, Japan.
| | - Wei-Hung Hsu
- Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan.
| | - Saulius Juodkazis
- Nanotechnology Facility, Center for Micro-Photonics, Swinburne University of Technology, Hawthorn, VIC 3122, Australia.
- Melbourne Centre for Nanofabrication, the Victorian Node of the Australian National Fabrication Facility, Clayton, VIC 3168, Australia.
| | - Koji Hatanaka
- Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan.
- College of Engineering, Chang Gung University, Taoyuan 33302, Taiwan.
- Department of Materials Science and Engineering, National Dong-Hwa University, Hualien 97401, Taiwan.
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Hsu WH, Masim FCP, Balčytis A, Juodkazis S, Hatanaka K. Dynamic position shifts of X-ray emission from a water film induced by a pair of time-delayed femtosecond laser pulses. OPTICS EXPRESS 2017; 25:24109-24118. [PMID: 29041357 DOI: 10.1364/oe.25.024109] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Femtosecond double-pulsed laser excitation of a water film in air showed enhancements of X-ray intensity as compared with single pulse irradiation. The position of the highest yield of X-rays strongly depends on temporal separation between the pre-pulse and the main-pulse (energy ratios where ∼ 1 : 10). The strongest X-ray emission was observed at 10-15 ns delay of the main-pulse. Nanoscale roughening of water surface can account for the observation.
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