Research

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9 pages, 3096 KiB

Open AccessCommunication

Wavelength Conversion of Multi-Joule Energy 532 nm Pulse Bursts via a Potassium Gadolinium Tungstate Raman Laser

by Aleksandr Tarasov and Hong Chu

Appl. Sci. 2023, 13(18), 10195; https://doi.org/10.3390/app131810195 - 11 Sep 2023

Cited by 1 | Viewed by 621

In this study, pulse bursts at 559, 589, and 621 nm, with a record energy of ~10 J, are generated using a KGW Raman laser with an external resonator, while pumping at 532 nm. The pulse bursts have a 10 ms duration, and [...] Read more.

In this study, pulse bursts at 559, 589, and 621 nm, with a record energy of ~10 J, are generated using a KGW Raman laser with an external resonator, while pumping at 532 nm. The pulse bursts have a 10 ms duration, and consist of 78 subpulses with a duration of <10 ns, at 8 kHz. The maximum energy of the bursts is restricted only by the characteristics of the Nd: YAG laser used as the 532 nm pump source, and can be increased. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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13 pages, 11864 KiB

Open AccessArticle

Direct Fabrication of Ultrahydrophobic Laser-Induced Graphene for Strain Sensors

by Devanarayanan Meena Narayana Menon, Matteo Giardino and Davide Janner

Appl. Sci. 2023, 13(8), 4935; https://doi.org/10.3390/app13084935 - 14 Apr 2023

Cited by 5 | Viewed by 2397

Abstract

Laser-induced graphene (LIG) has garnered tremendous attention in the past decade as a flexible, scalable, and patternable alternative for fabricating electronic sensors. Superhydrophobic and superhydrophilic variants of LIG have been demonstrated by previous studies. However, stability analysis of the superhydrophobic surface property has [...] Read more.

Laser-induced graphene (LIG) has garnered tremendous attention in the past decade as a flexible, scalable, and patternable alternative for fabricating electronic sensors. Superhydrophobic and superhydrophilic variants of LIG have been demonstrated by previous studies. However, stability analysis of the superhydrophobic surface property has not been explored. In this study, we use an infrared nanosecond laser to fabricate reduced graphene oxide (rGO)-based strain sensor on a carbon fiber reinforced polymer (CFRP) composite substrate. The fabricated sensor is characterized to determine its gauge factor using a three-point bend test demonstrating a gauge factor of 40. The fabricated LIG exhibits excellent superhydrophobic properties with a high contact angle (>160°). Both superhydrophobicity and piezoresistivity of the LIG under water immersion are studied for 25 h, demonstrating high stability. The obtained results could be of interest to several sectors, especially for maritime and high humidity applications. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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11 pages, 3011 KiB

Open AccessArticle

Supercontinuum Induced by Filamentation of Bessel-Gaussian and Laguerre-Gaussian Beams in Water

by Jiabin Wu, Li Huo, Yingxue Ni, Zhiyong Wu, Tao Chen, Shijie Gao and Suyu Li

Appl. Sci. 2022, 12(12), 6005; https://doi.org/10.3390/app12126005 - 13 Jun 2022

Cited by 4 | Viewed by 1260

Abstract

In this paper, we study the characteristics of the supercontinuum (SC) induced by the filamentation of two typical vortex beams (i.e., Laguerre-Gaussian (LG) and Bessel-Gaussian (BG) beams) in water. By moving the cuvette filled with water along the laser propagation path, we measure [...] Read more.

In this paper, we study the characteristics of the supercontinuum (SC) induced by the filamentation of two typical vortex beams (i.e., Laguerre-Gaussian (LG) and Bessel-Gaussian (BG) beams) in water. By moving the cuvette filled with water along the laser propagation path, we measure the SC induced by the filamentation of the two vortex beams at different positions in water. The results show that the degree of spectral broadening induced by the filamentation of LG beams hardly changes with the change of position, while for BG beams, the spectral broadening induced by filamentation is weak on both sides and strong in the middle. The value of topological charge (TC) affects the length of the filament formed by BG beams; however, its effect on the spectral broadening induced by the filamentation of LG and BG beams is negligible. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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15 pages, 7123 KiB

Open AccessArticle

Femtosecond Laser Direct Writing of Gradient Index Fresnel Lens in GeS₂-Based Chalcogenide Glass for Imaging Applications

by Pierre Delullier, Guillaume Druart, Florence De La Barrière, Laurent Calvez and Matthieu Lancry

Appl. Sci. 2022, 12(9), 4490; https://doi.org/10.3390/app12094490 - 28 Apr 2022

Cited by 7 | Viewed by 1953

Abstract

Chalcogenide glasses have attracted growing interest for their potential to meet the demands of photonic applications in the Mid-Wavelength InfraRed (MWIR) and Long-Wavelength InfraRed (LWIR) transmission windows. In this work, we investigated the photosensitivity to femtosecond laser irradiation of a dedicated chalcogenide glass, [...] Read more.

Chalcogenide glasses have attracted growing interest for their potential to meet the demands of photonic applications in the Mid-Wavelength InfraRed (MWIR) and Long-Wavelength InfraRed (LWIR) transmission windows. In this work, we investigated the photosensitivity to femtosecond laser irradiation of a dedicated chalcogenide glass, along with its possible applications in micro-optics. In order to address the SWaP problem (Size, Weight and Power), this work took advantage of recent techniques in femtosecond laser direct writing to imprint flat and integrated optical systems. Here, we wanted to simplify an infrared multispectral imaging system which combines a lens array and a filter array. Each channel has a focal length of 7 mm and an f-number of 4. We show in this paper that the chosen GeS₂-based chalcogenide glass is very promising for the fabrication of graded index optics by fs-laser writing, and particularly for the fabrication of Fresnel lenses. We note a very important phase variation capacity in this infrared material corresponding to refractive index variations up to +0.055. A prototype of Fresnel GRIN lens with a refractive index gradient was fabricated and optically characterized in the Vis range. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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13 pages, 3379 KiB

Open AccessArticle

Linear and Non-Linear Population Retrieval with Femtosecond Optical Pumping of Molecular Crystals for the Generalised Uniaxial and Biaxial Systems

by Christopher D. M. Hutchison, Alisia Fadini and Jasper J. van Thor

Appl. Sci. 2022, 12(9), 4309; https://doi.org/10.3390/app12094309 - 24 Apr 2022

Viewed by 1899

Abstract

Femtosecond optical measurements of photoexcitable molecular crystals carry ultrafast dynamics information with structural sensitivity. The creation and detection of transient dynamics depend on the optical parameters, as well as the explicit molecular structure, crystal symmetry, crystal orientation, polarisation of the photoexciting beam, and [...] Read more.

Femtosecond optical measurements of photoexcitable molecular crystals carry ultrafast dynamics information with structural sensitivity. The creation and detection of transient dynamics depend on the optical parameters, as well as the explicit molecular structure, crystal symmetry, crystal orientation, polarisation of the photoexciting beam, and interaction geometry. In order to retrieve the linear and non-linear population transfer in photoexcited crystals, excitation theory is combined here with the calculation of birefringence decomposition and is shown for both the generalised uniaxial and biaxial systems. A computational tool was constructed based on this treatment to allow modelling of electric field decomposition, dipole projections, and non-linear excitation population levels. This is available open source and with a GUI for ease of use. Such work has applications in two areas of ultrafast science: multidimensional optical crystallography and femtosecond time-resolved X-ray crystallography. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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11 pages, 3190 KiB

Open AccessArticle

Infrared Nanosecond Laser Texturing of Cu-Doped Bioresorbable Calcium Phosphate Glasses

by Devanarayanan Meena Narayana Menon, Diego Pugliese and Davide Janner

Appl. Sci. 2022, 12(7), 3516; https://doi.org/10.3390/app12073516 - 30 Mar 2022

Cited by 5 | Viewed by 1825

Abstract

The surface modification of bioactive glasses significantly impacts their performance for in-vivo biomedical applications. An affordable nanosecond pulsed laser surface-modification technique would provide great flexibility in applications such as cell scaffolding and fouling/anti-fouling engineered surfaces. This study reports on an infrared nanosecond laser [...] Read more.

The surface modification of bioactive glasses significantly impacts their performance for in-vivo biomedical applications. An affordable nanosecond pulsed laser surface-modification technique would provide great flexibility in applications such as cell scaffolding and fouling/anti-fouling engineered surfaces. This study reports on an infrared nanosecond laser modification technique we developed and applied to a Cu-doped bioresorbable calcium phosphate glass. With this technique, clean micro-protrusion features could be produced. By tuning the laser parameters such as the laser scan speed and average power, the width and height of the formed protrusions could be controlled. Finally, optimal laser parameters were defined to obtain complex surface textures without significant damage or thermal-stress-induced cracks. These results could provide effective aid for the affordable, fast, and selective surface texturing of metal-doped bioglasses, opening new possibilities in their application in the biological field. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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15 pages, 3548 KiB

Open AccessArticle

A Compact Accelerator-Based Light Source for High-Power, Full-Bandwidth Tunable Coherent THz Generation

by Kaiqing Zhang, Yin Kang, Tao Liu, Zhen Wang, Chao Feng, Wencheng Fang and Zhentang Zhao

Appl. Sci. 2021, 11(24), 11850; https://doi.org/10.3390/app112411850 - 13 Dec 2021

Cited by 4 | Viewed by 2202

Abstract

Terahertz (THz) radiation sources are increasingly significant for many scientific frontiers, while the generation of THz radiation with high-power at wide-tunable frequencies is still a limitation for most existing methods. In this paper, a compact accelerator-based light source is proposed to produce coherent [...] Read more.

Terahertz (THz) radiation sources are increasingly significant for many scientific frontiers, while the generation of THz radiation with high-power at wide-tunable frequencies is still a limitation for most existing methods. In this paper, a compact accelerator-based light source is proposed to produce coherent THz radiation with high pulse energy and tunable frequency from 0.1 THz to 60 THz. By using a frequency beating laser-modulated electron beam and undulator taper, intense coherent THz radiation can be generated through undulators. Theoretical analysis and numerical simulations demonstrate that the proposed technique can generate narrow-bandwidth THz radiation with a pulse energy up to 6.3 millijoule (mJ) and the three-dimensional effects of beam has limited influence on its performance. The proposed technique will open up new opportunities for THz spectroscopic and time-resolved experiments. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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12 pages, 937 KiB

Open AccessArticle

Drude-Lorentz Model for Optical Properties of Photoexcited Transition Metals under Electron-Phonon Nonequilibrium

by Elena Silaeva, Louis Saddier and Jean-Philippe Colombier

Appl. Sci. 2021, 11(21), 9902; https://doi.org/10.3390/app11219902 - 23 Oct 2021

Cited by 16 | Viewed by 6552

Abstract

Evaluating the optical properties of matter under the action of ultrafast light is crucial in modeling laser–surface interaction and interpreting laser processing experiments. We report optimized coefficients for the Drude-Lorentz model describing the permittivity of several transition metals (Cr, W, Ti, Fe, Au, [...] Read more.

Evaluating the optical properties of matter under the action of ultrafast light is crucial in modeling laser–surface interaction and interpreting laser processing experiments. We report optimized coefficients for the Drude-Lorentz model describing the permittivity of several transition metals (Cr, W, Ti, Fe, Au, and Ni) under electron-phonon nonequilibrium, with electrons heated up to 30,000 K and the lattice staying cold at 300 K. A Basin-hopping algorithm is used to fit the Drude-Lorentz model to the nonequilibrium permittivity calculated using ab initio methods. The fitting coefficients are provided and can be easily inserted into any calculation requiring the optical response of the metals during ultrafast irradiation. Moreover, our results shed light on the electronic structure modifications and the relative contributions of intraband and interband optical transitions at high electron temperatures corresponding to the laser excitation fluence used for surface nanostructuring. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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Graphical abstract

10 pages, 2372 KiB

Open AccessArticle

Realization of a Continuously Phase-Locked Few-Cycle Deep-UV/XUV Pump-Probe Beamline with Attosecond Precision for Ultrafast Spectroscopy

by Tsendsuren Khurelbaatar, Alexander Gliserin, Je-Hoi Mun, Jaeuk Heo, Yunman Lee and Dong-Eon Kim

Appl. Sci. 2021, 11(15), 6840; https://doi.org/10.3390/app11156840 - 25 Jul 2021

Cited by 1 | Viewed by 1980

Abstract

Chemical and physical processes in molecules can be controlled through the manipulation of quantum interferences between rotational, vibrational, and electronic degrees of freedom. Most of the past efforts have been focused on the control of nuclear dynamics. Even though electronic coherence and its [...] Read more.

Chemical and physical processes in molecules can be controlled through the manipulation of quantum interferences between rotational, vibrational, and electronic degrees of freedom. Most of the past efforts have been focused on the control of nuclear dynamics. Even though electronic coherence and its coupling to nuclear degrees of freedom may profoundly affect the outcome of these processes, electron dynamics have received less attention. Proper investigation of electron dynamics in materials demands ultrafast sources in the visible, ultraviolet (UV), and extreme ultraviolet (XUV) spectral region. For this purpose, a few-cycle deep-UV and XUV beamlines have been constructed for studying ultrafast electron dynamics in molecules. To ensure the required high temporal resolution on the attosecond time scale, vibration isolation from environmental mechanical noise and active stabilization have been implemented to achieve attosecond timing control between pump and probe pulses with excellent stability. This is achieved with an actively phase-stabilized double-layer Mach-Zehnder interferometer system capable of continuous time-delay scans over a range of 200 fs with a root-mean-square timing jitter of only 13 as over a few seconds and ~80 as of peak-to-peak drift over several hours. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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9 pages, 840 KiB

Open AccessArticle

Few-Cycle, μJ-Class, Deep-UV Source from Gas Media

by Tsendsuren Khurelbaatar, Je-Hoi Mun, Jaeuk Heo, Yunman Lee and Dong-Eon Kim

Appl. Sci. 2021, 11(14), 6440; https://doi.org/10.3390/app11146440 - 13 Jul 2021

Viewed by 2026

Abstract

Energetic, few-fs pulses in the deep-UV region are highly desirable for exploring ultrafast processes on their natural time scales, especially in molecules. The deep-UV source can be generated from gas media irradiated with few-cycle near-infrared laser pulses via a third-order frequency conversion process, [...] Read more.

Energetic, few-fs pulses in the deep-UV region are highly desirable for exploring ultrafast processes on their natural time scales, especially in molecules. The deep-UV source can be generated from gas media irradiated with few-cycle near-infrared laser pulses via a third-order frequency conversion process, which is a perturbative mechanism in a relatively weak field regime. In this work, we demonstrate that the deep-UV generation process is significantly affected by also even higher nonlinear processes, such as the ionization depletion of gas and plasma-induced spatiotemporal distortion of propagating light. In the experiment, by optimizing the deep-UV (3.6–5.7 eV) generation efficiency, the highest deep-UV energy of 1 μJ was observed from a moderately ionized 0.8-bar Ar gas target. The observed UV spectra exhibited frequency shifts depending on the experimental conditions—gas type, gas pressure, and the gas cell location—supporting the importance of the highly nonlinear mechanisms. The experimental observations were well corroborated by numerical simulations. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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Review

Jump to: Research

23 pages, 11989 KiB

Open AccessReview

Laser Cavitation Peening: A Review

by Hitoshi Soyama and Yuka Iga

Appl. Sci. 2023, 13(11), 6702; https://doi.org/10.3390/app13116702 - 31 May 2023

Cited by 7 | Viewed by 1359

Abstract

During submerged laser peening using a pulsed laser, a bubble that behaves like cavitation is generated after laser ablation (LA). The bubble is referred to as laser cavitation (LC). The amplitude of the shockwave in water generated by LA is larger than that [...] Read more.

During submerged laser peening using a pulsed laser, a bubble that behaves like cavitation is generated after laser ablation (LA). The bubble is referred to as laser cavitation (LC). The amplitude of the shockwave in water generated by LA is larger than that of LC; however, the impact passing through the target metal during LC is larger than that of LA. LC impact can be utilized for peening at optimized conditions. Thus, submerged laser peening is referred to as “laser cavitation peening”, as the peening method using the cavitation impact is known as “cavitation peening”. The impact induced by a hemispherical bubble is more aggressive than that of a spherical bubble with a microjet. Laser cavitation peening can improve the fatigue strength of metallic materials by producing work-hardening and introducing compressive residual stress. Three-dimensional additively manufactured metals (3D metals) such as titanium alloy are attractive materials for aviation components and medical implants; however, the fatigue strength of as-built components is nearly half of that of bulk metals, and this is an obstacle for the applications of 3D metals. In the present study, published research papers are reviewed to identify the key factors of laser cavitation peening, with additional visualization of LC and data. Then, improvements in the fatigue strength of metallic materials, including 3D metals treated by laser cavitation peening, are summarized. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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16 pages, 2298 KiB

Open AccessEditor’s ChoiceReview

Orthopedics-Related Applications of Ultrafast Laser and Its Recent Advances

by Celina L. Li, Carl J. Fisher, Ray Burke and Stefan Andersson-Engels

Appl. Sci. 2022, 12(8), 3957; https://doi.org/10.3390/app12083957 - 14 Apr 2022

Cited by 14 | Viewed by 3066

Abstract

The potential of ultrafast lasers (pico- to femtosecond) in orthopedics-related procedures has been studied extensively for clinical adoption. As compared to conventional laser systems with continuous wave or longer wave pulse, ultrafast lasers provide advantages such as higher precision and minimal collateral thermal [...] Read more.

The potential of ultrafast lasers (pico- to femtosecond) in orthopedics-related procedures has been studied extensively for clinical adoption. As compared to conventional laser systems with continuous wave or longer wave pulse, ultrafast lasers provide advantages such as higher precision and minimal collateral thermal damages. Translation to surgical applications in the clinic has been restrained by limitations of material removal rate and pulse average power, whereas the use in surface texturing of implants has become more refined to greatly improve bioactivation and osteointegration within bone matrices. With recent advances, we review the advantages and limitations of ultrafast lasers, specifically in orthopedic bone ablation as well as bone implant laser texturing, and consider the difficulties encountered within orthopedic surgical applications where ultrafast lasers could provide a benefit. We conclude by proposing our perspectives on applications where ultrafast lasers could be of advantage, specifically due to the non-thermal nature of ablation and control of cutting. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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11 pages, 3575 KiB

Open AccessReview

Line-Shaped Illumination: A Promising Configuration for a Flexible Two-Photon Microscopy Setup

by Jacopo Parravicini, Elton Hasani and Luca Tartara

Appl. Sci. 2022, 12(8), 3938; https://doi.org/10.3390/app12083938 - 13 Apr 2022

Viewed by 1420

Abstract

An innovative two-photon microscope exploiting a line-shaped illumination has been recently devised and then implemented. Such configuration allows to carry out a real-time detection by means of standard CCD cameras and is able to maintain the same resolution as commonly used point-scanning devices, [...] Read more.

An innovative two-photon microscope exploiting a line-shaped illumination has been recently devised and then implemented. Such configuration allows to carry out a real-time detection by means of standard CCD cameras and is able to maintain the same resolution as commonly used point-scanning devices, thus overcoming what is usually regarded as the main limitation of line-scanning microscopes. Here, we provide an overview of the applications in which this device has been tested and has proved to be a flexible and efficient tool, namely imaging of biological samples, in-depth sample reconstruction, two-photon spectra detection, and dye cross-section measurements. These results demonstrate that the considered setup is promising for future developments in many areas of research and applications. Full article

(This article belongs to the Special Issue Applications of Pulsed/Ultrafast Lasers in Spectroscopy, Biophotonics, and Micromachining)

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