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1 kHz dual sub-pulse train picosecond radially polarized beam KGW Raman generator capable of achieving multiple optical communication wavelength
摘要： A dual sub-pulse train 1064 nm picosecond radially polarized beam pump KGW single-pass Raman generator was designed. The Stokes lines of both the 768 cm?1 and 901 cm?1 vibrational modes of the KGW Raman-active crystal were excited simultaneously. The Raman generator radiated up to seven Stokes lines in the infrared spectrum, which covered multiple optical communication channels. The overall Stokes average power reached 1.01 W, and the maximum Raman overall conversion efficiency was 23.1%. The interaction between the optical field and the Raman crystal was discussed from two perspectives of line width compression and beam quality.
关键词： Multi-wavelength KGW Raman laser,Nonlinear optics,Dual sub-pulse train picosecond laser,Infrared spectrum,Radially polarized beam
更新于2025-09-12 10:27:22
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Eruptive Keratoacanthomas in a Red Tattoo After Treatment With a 532-nm Picosecond Laser
摘要： Decorative tattooing continues to be popular, with remorse and request for tattoo removal common in a significant percentage of the tattooed population. Tattoo removal carries complications including inflammatory reactions, infections, and malignancies. Many of these complications are reported to be more frequent in red tattoo ink, conceivably due to the inflammatory nature of the specific components of the red ink particles. Keratoacanthomas (KA) are considered a low-risk form of squamous cell carcinoma (SCC), often associated with injury such as surgery, trauma, and burns. While their association with tattoos has been reported, the eruption of KAs after attempted tattoo removal has not. We report a case of eruptive KAs after tattoo removal using a picosecond laser at an outside facility.
关键词： keratoacanthomas,picosecond laser,red tattoo ink,tattoo removal
更新于2025-09-12 10:27:22
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Electron Microscopy of Argyria Treated With Picosecond Alexandrite Laser
摘要： Argyria (from the Greek word for silver, argyros) is the bluish gray discoloration of tissue caused by exposure to silver or its salts, often because of alternative medicine treatment or occasionally through occupational exposure. Since the 1990s, colloidal silver has been available in pharmacy-supplied dietary supplements and homeopathic remedies for the treatment of various diseases, including cancer, immunodeficiency, chronic fatigue, tuberculosis, and other infections, without any substantiating evidence. Long-term consumption of silver products can lead to chronic argyria, with silver deposition in organs, including the skin, liver, spleen, kidneys, and central and peripheral nervous system. Generalized argyria can occur when silver compounds are ingested, applied topically, or inhaled. Argyria can also be localized to certain sites of the skin or eyes if creams or eye drops are used or can be found on the ear lobes when silver earrings are worn. Silver deposits may localize in the eccrine glands of the skin, as well as in the papillary dermis and pilosebaceous follicles. The silver is in the form of silver sulfide and appears to be more abundant in the sun-exposed skin. Argyria has a well-defined toxicity, and discoloration is permanent. Recently, Q-switched nanosecond laser and picosecond alexandrite laser (PicoSure, Cynosure) have been used to treat argyria. Both the Q-switched nanosecond laser and the picosecond alexandrite laser use the principle of selective photothermolysis and have been used in a number of applications, including tattoo removal and pigmentation removal. Pulses of light energy is delivered to the skin and causes fragmentation of ink particles, allowing for phagocytosis and removal of the pigment by macrophages. It is speculated that laser treatment of argyria causes fragmentation of silver deposits in the skin, similar to the mechanisms of tattoo removal. We present a case report of the successful treatment of argyria with picosecond alexandrite laser, as demonstrated by clinical photographs, histopathology, and electron microscopy. This case provides evidence that picosecond laser causes the fragmentation of silver particles in argyria without phagocytosis in the immediate post-treatment phase.
关键词： picosecond alexandrite laser,silver particles,argyria,laser treatment,electron microscopy
更新于2025-09-12 10:27:22
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Use of Lasers for Iron-Induced Accidental Tattoos
摘要： BACKGROUND Awareness of accidental tattoos after iron injections with paravenous leakage is low. No larger patient cohorts have been analyzed. The lesions are a burden to the patients. The only known treatment is laser therapy. OBJECTIVE To characterize the clinical appearance and development of iron-induced tattoos and to demonstrate safe and efficient removal with quality-switched (QS) and picosecond lasers. MATERIALS AND METHODS The authors conducted a retrospective systematic analysis on patients who presented at the Dermatology Department of the University Hospital of Zurich between Year 2008 and 2017 with accidental hyperpigmentations after iron injections. From 29 collected patients, 13 received laser treatment and were analyzed with reference to the lasers used, including wavelength, fluence, spot size, intervals, number of sessions, and overall success. The authors defined the latter as a complete removal or as patients’ satisfaction. RESULTS The authors treated 13 patients and completed the treatment in 8 patients, with an average of 5.6 sessions. No complications occurred. CONCLUSION Spontaneous regression of iron-induced tattoos is possible within 1 to 2 years, but not guaranteed. Removal with QS ruby, Nd:YAG, and picosecond lasers can be achieved within a mean number of 5.6 sessions. Assuring a valid indication before intravenous iron administration is important.
关键词： picosecond lasers,iron-induced tattoos,hyperpigmentation,quality-switched lasers,laser therapy
更新于2025-09-12 10:27:22
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Investigation of dielectric layers laser ablation mechanism on n-PERT silicon solar cells for (Ni) plating process: Laser impact on surface morphology, composition, electrical properties and metallization quality
摘要： Laser contact opening is a critical step for solar cells manufacturing and needs to be optimized to achieve high efficiencies. In this paper, laser contact opening using a picosecond laser (wavelength 355 nm, pulse duration 10 ps) has been carried out on n-PERT precursors composed of a SiOx/SiOxNy stack on the rear polished side and a SiOxNy layer on the front textured side. By varying peak fluence from 0.130 J/cm2 to 2.159 J/cm2 and spot overlapping, ninety parameters combinations have been tested to open these dielectric layers. Surface morphology characterization, before and after laser ablation, has been realized using Confocal Laser Scanning Microscopy and Scanning Electron Microscopy. Bulk and surface compositions have also been investigated by Energy Dispersive Spectroscopy and X-ray Photoelectron Spectroscopy analysis, respectively. Results have shown the existence of four separated laser impacted areas on the polished side and a related ablation mechanism is suggested. Also, electrical characterization using four probe measurements and calibrated lifetime photoluminescence revealed that electrical properties of the silicon underlying increased when post laser annealing was performed associated with no spot overlapping. Then, nickel electroless deposition has been performed and first characterizations indicate adherence issues and inhomogeneous metallization. Characterization of metallized samples revealed that these observations were closely linked to the non-homogenous surface morphology and composition after laser ablation.
关键词： Ni plating,Surface damages,n-PERT cell,Ablation mechanism,UV-Picosecond laser
更新于2025-09-12 10:27:22
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Innovative Sub-5 Micron Microvias by Picosecond UV Laser for Post-Moore Packaging Interconnects
摘要： This paper presents for the first time microvias scaled down to sub-5 μm in diameter fabricated using picosecond UV laser ablation in a non-photoimageable dielectric film. The motivation of this work is to address post-Moore and More-than- Moore packaging interconnect needs. Microvias play a critical role in package interconnections in IO density and the IC bump pitch for 2.5D interposers and fan-out packages. UV laser ablation has been the key technology for fabricating small microvias in high density interconnect (HDI) packaging for more than two decades. The state-of-the-art microvia fabricated by UV laser ablation is still at 20 μm in diameter and 50 μm in pitch. This study explores the feasibility of fabricating microvias of 5 μm or less in diameter with a commercially available picosecond UV laser system. The experimental results show that microvias of 5 μm or less in diameter in a 5 μm thick Ajinomoto buildup dielectric film (ABF) are achieved. This paper also addresses fundamentals of picosecond pulsed laser ablation on polymer dielectric materials, and process optimization to generate sub-5 micron microvias. The via pitch of 8 μm to 12 μm is demonstrated. UV laser ablation also addresses the issue of limited availability of photosensitive dielectric materials for photolithography based microvia fabrication.
关键词： RDL,2.5D interposer,fan-out package,Microvia,interconnect,picosecond UV laser
更新于2025-09-12 10:27:22
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Combination of Dual Wavelength Picosecond and Nanosecond Pulse Width Neodymium‐Doped Yttrium–Aluminum–Garnet Lasers for Tattoo Removal
摘要： Background and Objectives: Tattoo removal by laser has been mostly performed using Q‐switched laser, which has nanosecond pulse width. In recent years, the efficacy of treatment with picosecond pulse width laser has also been reported. Study Design/Materials and Methods: Using yttrium–aluminum–garnet laser with a potassium‐titanyl‐phosphate frequency‐doubling crystal, we performed a retrospective clinical study with combination treatment using pulse widths of 750 ps and 2 ns. The number of treatments was compared with the Kirby–Desai score. Tissue changes immediately after laser irradiation at 2 ns and 750 ps were compared using an electron microscope. Results: The combination treatment using pulse widths of 2 ns and 750 ps was safe and more effective than the Q‐switched neodymium‐doped yttrium–aluminum–garnet laser treatment. Tattoo removal was possible with significantly fewer treatment numbers than the Kirby–Desai score, without adverse events. The results from the scanning electron microscope revealed that ink particles irradiated by 750 ps were more dispersed than those by 2 ns. Conclusions: The combination treatment with pulse widths of 2 ns and 750 ps and 1064 nm and 532 nm wavelengths using the neodymium‐doped yttrium–aluminum–garnet laser was safe and effective and can be a useful option for tattoo removal.
关键词： tattoo removal,2 nanosecond,laser treatment,dual wavelength laser,750 picosecond
更新于2025-09-12 10:27:22
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Uniform and smooth molybdenum film produced through picosecond pulsed laser deposition
摘要： An approach to achieve uniform and smooth molybdenum (Mo) ?lm on a BK7 glass plate at room temperature is proposed through picosecond pulsed laser deposition, with the pulsed laser radiating the target along a linear track. A numerical model is established to analyze the in?uence of linear scanning offsets on the thickness homogeneity of the deposited thin ?lm. Through an appropriate choice of radiation intensity and scanning parameters, a uniform and smooth layer of Mo thin ?lm is prepared with its maximum thickness variation and root-mean-square roughness better than 5% and 1.2 nm, respectively.
关键词： picosecond pulsed laser deposition,smooth,numerical model,molybdenum film,uniform
更新于2025-09-11 14:15:04
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Efficacy and Safety of Ablative Resurfacing With A High‐Energy 1,064 Nd‐YAG Picosecond‐domain Laser for the Treatment of Facial Acne Scars in Asians
摘要： Objectives: There have been few studies regarding the use of a picosecond‐domain laser for acne scars in Asians. This prospective study evaluated the efficacy and safety of a high‐energy 1,064 nm Nd:YAG picosecond‐domain laser for ablation and resurfacing of facial acne scars in Asians. Methods: Subjects were treated with a 1,064 nm picosecond laser (8 mm spot, 0.7–1.0 J/cm2, 5 Hz) every 4 weeks for three sessions. Two blinded dermatologists evaluated the pre‐ and 3‐month post‐treatment images with a 10‐point improvement scale. Subject pain, global improvement, and satisfaction were also assessed. The Facial Acne Scar Quality of Life (FASQoL) questionnaire was used to evaluate the subjects’ quality of life. Results: Twenty subjects aged 18–50 years with Fitzpatrick skin type III–V were enrolled. The median dermatologist‐rated improvement score was 3 out of 10. Subjects were satisfied to very satisfied with global improvement. Subjects’ quality of life significantly improved with a median FASQoL score of 10 after treatment compared with 21 before treatment (P < 0.001). Adverse effects were limited to erythema, pain, and edema without postinflammatory hyperpigmentation. Conclusions: The 1,064 nm picosecond‐domain laser with ablative resurfacing parameters is safe and effective for the treatment of acne scars in Asians. Lasers Surg. Med. ? 2019 Wiley Periodicals, Inc.
关键词： treatment,laser,picosecond,acne scars,fractionated
更新于2025-09-11 14:15:04
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Electromagnetic field growth triggering super-ponderomotive electron acceleration during multi-picosecond laser-plasma interaction
摘要： The dependence of the mean kinetic energy of laser-accelerated relativistic electrons (REs) on the laser intensity, so-called ponderomotive scaling, explains well the experimental results to date; however, this scaling is no longer applicable to multi-picosecond (multi-ps) laser experiments. Here, the production of REs was experimentally investigated via multi-ps relativistic laser–plasma-interaction (LPI). The lower slope temperature shows little dependence on the pulse duration and is close to the ponderomotive scaling value, while the higher slope temperature appears to be affected by the pulse duration. The higher slope temperature is far beyond the ponderomotive scaling value, which indicates super-ponderomotive REs (SP-REs). Simulation and experimental evidence are provided to indicate that the SP-REs are produced by LPI in an under-critical plasma, where a large quasi-static electromagnetic field grows rapidly after a threshold timing during multi-ps LPI.
关键词： relativistic electrons,electromagnetic field growth,super-ponderomotive acceleration,laser-plasma interaction,multi-picosecond laser
更新于2025-09-11 14:15:04