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The implementation and data analysis of an interferometer for intense short pulse laser experiments
摘要： We present an interferometry setup and the detailed fringe analysis method for intense short pulse (SP) laser experiments. The interferometry scheme was re?ned through multiple campaigns to investigate the effects of pre-plasmas on energetic electrons at the Jupiter Laser Facility at Lawrence Livermore National Laboratory. The interferometer used a frequency doubled (λ = 0.527 μm) 0.5 ps long optical probe beam to measure the pre-plasma density, an invaluable parameter to better understand how varying pre-plasma conditions affect the characteristics of the energetic electrons. The hardware of the diagnostic, data analysis and example data are presented. The diagnostic setup and the analysis procedure can be employed for any other SP laser experiments and interferograms, respectively.
关键词： short pulse laser,optical interferometry,Mach–Zehnder interferometer,picosecond probe,plasma density
更新于2025-09-19 17:13:59
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Investigation of picosecond thermodynamics in a laser-produced plasma using Thomson scattering
摘要： The picosecond evolution of the plasma conditions in a laser-produced plasma was measured using a Thomson-scattering diagnostic. The picosecond resolved Thomson spectra was enabled by a pulse-front-tilt-compensated spectrometer. The Thomson spectra revealed a transition in the plasma conditions from an initially cold evolving plasma to a quasi-stationary equilibrium plasma. The equilibrium temperature was found to match the generalized heat equation’s predicted scaling Te ∝ n2/5 and Te ∝ I 1/5. The plasma evolution was compared to Raman gain bandwidth calculations and showed a time-dependent resonance detuning that would limit the transfer e?ciency of a Raman plasma ampli?er in the linear regime.
关键词： laser-produced plasma,Thomson scattering,picosecond thermodynamics,Raman plasma amplifier,plasma conditions
更新于2025-09-19 17:13:59
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Use of a Picosecond Alexandrite Laser for Treating Acquired Bilateral Nevus of Ota-Like Macules in Chinese Patients
摘要： Background and Objectives: Acquired bilateral nevus of Ota‐like macules (ABNOM) is common among the Chinese population. There have been few studies on the use of a picosecond alexandrite laser for the treatment of ABNOMs. The goal of this study was to evaluate the efficacy and safety of a 755 nm picosecond alexandrite laser for the treatment of ABNOMs. Study Design/Materials and Methods: A total of 225 subjects diagnosed with ABNOMs were included in this retrospective study. A 755 nm picosecond alexandrite laser system was used to treat all subjects. The safety and effectiveness of the laser were determined using a clinical photo assessment. The correlating factors of the patients, including the age, Fitzpatrick skin type, lesion location, lesion color, treatment procedures, melasma, and outcomes, were analyzed. Results: The patients underwent one to four treatment sessions with clinical clearance (>90%) rates of 8.89%, 30.99%, 56.65%, and 60.00%, respectively. A higher number of sessions was positively associated with a better treatment response. The hyperpigmentation incidence rate was 22.67%, and one case of hypopigmentation was observed. Conclusion: Our results suggest that a picosecond alexandrite laser is an effective and safe approach for treating ABNOMs in Chinese patients.
关键词： acquired bilateral nevus of Ota‐like macules (ABNOM),picosecond alexandrite laser,treatment effect,post‐inflammatory hypopigmentation
更新于2025-09-19 17:13:59
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A Randomized, Splita??Face, Doublea??Blind Comparison Trial Between Fractionated Frequencya??Doubled 1064/532a??nm Picosecond Nd:YAG Laser and Fractionated 1927a??nm Thulium Fiber Laser for Facial Photorejuvenation
摘要： Fractionated lasers are a popular therapeutic option for facial photorejuvenation. In this study, we compare the safety, tolerability, and efficacy of a fractionated frequency‐doubled 1064/532 nm picosecond Nd:YAG fractionated picosecond laser (FPL) versus a fractionated 1927 nm thulium fiber laser (TFL) for facial rejuvenation. This was a double‐blind, randomized, split‐face comparison study involving 20 subjects. Facial halves were randomized to receive either FPL or TFL treatment. Three treatments were delivered at 1‐month intervals. Subjects were followed up for 1, 3, and 6 months post‐final treatment session and evaluated by blinded, non‐treating investigators for dyspigmentation, erythema, keratosis, texture, and rhytids on a standardized scale. Subjects also recorded a quantitative daily diary rating healing progress for 14 days after every treatment session. Statistically significant improvements in elastosis, erythema, keratosis, dyschromia, and skin texture were noted in both treatment groups. There were no significant differences detected in clinical efficacy between the two groups. Subject daily diaries revealed statistically significant differences in tolerability during the immediate 14‐day post‐operative recovery period. The facial half treated with FPL displayed significantly less redness on days 3 and 4; significantly less swelling on day 5; significantly less crusting on days 1 through 9; significantly less peeling on days 3 through 9; and significantly less itch on days 4 and 7. There were no unexpected adverse effects observed. Both FPL and TFL are safe and effective treatment options for facial rejuvenation. FPL may be associated with significantly less downtime.
关键词： photodamage,laser induced optical breakdown,photothermolysis,thulium fiber,picosecond laser,photoacoustolysis,Nd:YAG,holographic lens,clinical trial,rejuvenation
更新于2025-09-19 17:13:59
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Roughness and wettability properties of plain and silica-coated copper surfaces textured with picosecond laser
摘要： Many recent studies have investigated the mechanism of wettability transition of laser-textured copper surfaces on di?erent materials. Furthermore, several such studies have focused on approaches to accelerate wettability transition from hydrophilicity to hydrophobicity, such as temperature annealing and the use of chemical solutions. However, few researchers have focused on maintaining the initial hydrophilicity of laser-textured surfaces. This study presents a hybrid surface modi?cation method involving chemical bath deposition and ultrafast laser. First, the selected copper substrates are modi?ed using the sol-gel method through dip coating. Subsequently, the coated copper surfaces are irradiated with a picosecond laser. After laser texturing, bumpy structures are formed, and SiO2 nanoparticles can be sintered on the surfaces. Thus, the original hydrophilicity can be maintained, and the surface roughness can be enhanced simultaneously. By using this hybrid modi?cation method, a heterogeneous surface with high-precision patterns can be obtained. Moreover, the mechanism of wettability transition of laser-textured copper surfaces with di?erent laser ?uences is discussed using the Wenzel and Cassie Baxter wetting model by analyzing the chemical composition and surface morphology of the treated surfaces.
关键词： Roughness,Copper,Laser texturing,Wettability,Picosecond laser,Sol-gel
更新于2025-09-19 17:13:59
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Modification characteristics of filamentary traces induced by loosely focused picosecond laser in sapphire
摘要： The ability of loosely focused picosecond laser to induce filamentation (4.8 times the Rayleigh length) in sapphire was confirmed. The morphology and microstructure of the filamentary traces under typical pulse energy were studied, in which the colorful birefringence phenomenon and damage defects were detected in sapphire. Irreversible ceramic-like polycrystalline microstructures were formed in filamentary traces, and the phase transition from α-Al2O3 to γ-Al2O3 directly reflected the thermal effect of picosecond laser filamentation. According to the filamentary characteristics, a continuous filamentary channel with a uniform diameter of 33 μm and a length of 7443 μm was obtained by gradually raising the focal position. The research provides first-hand information for the high throughput micro-cutting, micro drilling and thin slicing of sapphire based on ultrafast laser non-linear effects.
关键词： Phase transition,Modification,Picosecond laser,Filamentation,Sapphire
更新于2025-09-19 17:13:59
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Retrospective photographic review of nontattoo indications treated by picosecond laser
摘要： Background: Picosecond (PS) lasers were approved by the US FDA in 2012 after being shown to remove tattoos with more success and fewer treatments compared with traditional methods. PS lasers were shown to be versatile, indicated for the treatment of lentigines, café-au-lait macules (CALMs), and acne scars and skin rejuvenation. Objective: We report our experience treating our patients for different indications using a PS laser. Methods: We performed a retrospective chart and photographic review of all patients seen between 2016 and 2018 that were treated in our centers with a PS laser for nontattoo indications. Clinical outcomes were evaluated using side-by-side comparisons of the clinical photographs by two blinded, independent physicians using a visual analog scale consisting of six levels of treatment response. Results: A total of 233 patients were studied. Most sought treatment for solar lentigo (27%) and skin rejuvenation (14%). Epidermal nevi exhibited the greatest improvement with treatment, while acne scarring demonstrated the least. Only 24% of patients experienced noteworthy, transient adverse effects. Conclusion: Picosecond lasers were efficacious and safe for a variety of indications. They were effective in treating epidermal nevi and pigmented lesions, such as Lentigines and CALMs.
关键词： aesthetic improvement,epidermal nevus,picosecond laser,laser treatment,solar lentigines
更新于2025-09-19 17:13:59
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Comparison of fractional neodymium-doped yttrium aluminum garnet (Nd:YAG) 1064-nm picosecond laser and fractional 1550-nm erbium fiber laser in facial acne scar treatment
摘要： To compare the safety and efficacy of fractional neodymium-doped yttrium aluminum garnet (Nd:YAG) 1064-nm picosecond laser and fractional 1550-nm erbium fiber laser in acne scar treatment and to assess the adverse effects and complications of the two devices. Thirty patients with cosmetically similar acne scars on both sides of the faces were enrolled and treated four times at 4-week intervals. Each side of the face was treated with either fractional 1064-nm Nd:YAG picosecond laser or fractional 1550-nm erbium fiber laser. Efficacy was evaluated using digital photography taken at baseline and 5 months by a blinded dermatologist using the ECCA grading scale (échelle d’évaluation clinique des cicatrices d’acné). Patient overall satisfaction and self-rated improvement scores were recorded at baseline and 5 months. Adverse effects were recorded at every visit. Twenty-seven patients completed the study. Both devices demonstrated significant median ECCA score improvement from baseline (P < 0.001). However, there was no significant difference between the two in terms of median ECCA score improvement, patients’ perception of scar improvement, and overall satisfaction. Considering the adverse effects, more pinpoint bleeding was significantly observed with the picosecond laser (P = 0.002), whereas more pain was noted with the erbium laser (P < 0.001). Both fractional 1064-nm Nd:YAG picosecond laser and fractional 1550-nm erbium fiber laser are safe and effective in the treatment of acne scars. Costs should be taken into consideration when deciding on which device to use to maximize treatment outcomes.
关键词： Erbium fiber laser,Acne scar,Picosecond laser,Acne scar treatment,Fractional laser
更新于2025-09-19 17:13:59
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High-order actively mode-locked picosecond fiber laser and Poissonian single-photon source
摘要： We propose a novel scheme of high-order actively mode-locked picosecond fiber laser based on the nonlinear polarization rotation in a semiconductor optical amplifier, and experimentally demonstrate the 200th-order mode locking with repetition frequency of ～ 1.19 GHz and pulse width of 1.63 ps. The fundamental repetition frequency is accurately obtained to be 5.9639 MHz by spectrum analysis. Our laser is much easier mode locked and stabler than passive mode-locked ones. Taking advantage of the ultra-stable mode-locked laser, we obtain practical quasi-single-photon (QSP) source. Statistic analyses show that it approaches closer to the Poisson distribution at lower count rate. In our experiment, at count rate of 9.7 kcps or QSP emitting rate of ～97 kcps, it obeys a perfect standard Poisson distribution. The laser is convenient to be upgraded for higher-order mode-locked at repetition frequency over 40 GHz, which are suitable to generate high-speed QSP source for future quantum communications.
关键词： Active mode-locked,Picosecond fiber lasers,Single photon source
更新于2025-09-16 10:30:52
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Successful treatment of ephelides in Asian skin using the picosecond 785‐nm laser
摘要： Background: For ethnic skin, laser surgery for pigmented lesions presents a special challenge due to the increased risk of postprocedural complications—erythema, blistering, and postinflammatory dyspigmentation. Aims: To describe the treatment of ephelides in Asian skin treated with a picosecond 785-nm laser. Patients/Methods: The first patient with ephelides on the cheeks and nose was treated with a picosecond 785-nm laser with the treatment parameter of 1.2 J/cm2 and 3-mm spot size. The second patient with ephelides on the cheeks was treated with a picosecond 785-nm laser with the treatment parameter of 1.3 J/cm2 and 3-mm spot size. Results: After a single laser session, both patients achieved appreciable improvement without any complications. Conclusion: This is the first case series demonstrating the efficacy and safety of the picosecond 785-nm laser for the treatment of ephelides in Asian skin.
关键词： ephelides,785-nm,Asian,picosecond,freckle
更新于2025-09-16 10:30:52