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External Field-Controlled Ablation: Magnetic Field
摘要： The femtosecond laser ablation of silicon amidst an externally applied magnetic ?eld in different orientations was investigated with respect to the scanning direction and polarisation of the laser beam, by observation of ablation patterns and debris displacement in a range of ?uences, magnetic ?elds strengths, and geometries. Ultra-short ～ 230 fs laser pulses of 1030 nm wavelengths were utilised in the single and multi-pulse irradiation modes. Ablation with an externally applied magnetic B-?eld Bext ≈ 0.15 T was shown to strongly affect debris formation and deposition. The mechanism of surface plasmon polariton (SPP) wave can explain the ablated periodic patterns observed with alignment along the magnetic ?eld lines. The application potential of external ?eld controlled ablation is discussed.
关键词： magnetic ?eld,ablation,femtosecond laser fabrication
更新于2025-09-11 14:15:04
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Damage analysis of a perfect broadband absorber by a femtosecond laser
摘要： Plasmonic metamaterial absorbers are particularly important in different applications such as photodetectors, microbolometers and solar cells. in this paper, we propose a tungsten boride (WB, a refractory ceramic) based broadband metamaterial absorber whose optical properties is numerically analyzed and experimentally characterized. We have also analyzed the damage characteristics of this absorber using a femtosecond laser and compared with an ordinary Au metamaterial absorber. We observe that WB has almost the double absorption bandwidth with absorption more than 90% over the spectral range of 950 to 1400 nm when compared with the Au counterpart. Furthermore, we show that Au metamaterial is damaged at the power of around 36.4 mW whereas WB metamaterial is not damaged at that power (WB has high tammann temperature than Au)-however the atom of WB material was knocked off by the bombardment of a femtosecond laser.
关键词： tungsten boride,femtosecond laser,broadband absorption,damage analysis,Plasmonic metamaterial absorbers
更新于2025-09-11 14:15:04
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Enzyme-Assisted Photoinjection of Megadalton Molecules into Intact Plant Cells Using Femtosecond Laser Amplifier
摘要： femtosecond laser photoporation has become a popular method to deliver various kinds of molecules such as genes, proteins, and fluorescent dyes into single mammalian cells. However, this method is not easily applied to plant cells because their cell wall and turgor pressure prevent the delivery, especially for larger molecules than the mesh size of the cell wall. This work is the first demonstration of the efficient photoinjection of megadalton molecules into a cytoplasm of an intact single plant cell by employing a femtosecond laser amplifier under moderate enzyme treatment conditions. The intense femtosecond laser pulse effectively formed a pore on the cell wall and membrane of Tobacco BY-2, and 2 MDa dextran molecules were introduced through the pore. Along with the pore formation, induced mechanical tensile stresses on BY-2 cells were considered to increase permeability of the cell membrane and enhance the uptake of large molecules. Moreover, the moderate enzyme treatment partially degraded the cell wall thereby facilitating the increase of the molecular introduction efficiency.
关键词： plant cells,femtosecond laser,megadalton molecules,photoinjection,enzyme treatment
更新于2025-09-11 14:15:04
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Robust Remote Sensing of Trace-Level Heavy-Metal Contaminants in Water Using Laser Filaments
摘要： Water is the major natural resource that enables life on our planet. Rapid detection of water pollution that occurs due to both human activity and natural cataclysms is imperative for environmental protection. Analytical chemistry–based techniques are generally not suitable for rapid monitoring because they involve collection of water samples and analysis in a laboratory. Laser-based approaches such as laser-induced breakdown spectroscopy (LIBS) may offer a powerful alternative, yet conventional LIBS relies on the use of tightly focused laser beams, requiring a stable air–water interface in a controlled environment. Reported here is a proof-of-principle, quantitative, simultaneous measurement of several representative heavy-metal contaminants in water, at ppm-level concentrations, using ultraintense femtosecond laser pulses propagating in air in the filamentation regime. This approach is straightforwardly extendable to kilometer-scale standoff distances, under adverse atmospheric conditions and is insensitive to the movements of the water surface due to the topography and water waves.
关键词： filamentation,heavy-metal pollution,femtosecond laser pulse,remote sensing
更新于2025-09-11 14:15:04
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Femtosecond laser-induced large area of periodic structures on chalcogenide glass via twice laser direct-writing scanning process
摘要： We presented a theoretical and experimental study for the evolution of femtosecond laser direct-writing induced large area of periodic surface structures on As2S3 glass. The laser direct-writing induced large area of low spatial frequency LIPSS (LSFL) structures can be fabricated with the overlap rate increases from 65% to 80%. The evolution process can be defined by the competition between the laser fluence and pulse overlap rate. What is more important is that, based on secondary femtosecond laser scanning process, the interaction between the initial LSFL structures induced by the first scanning and the laser pulse of the second scanning process can induce local field enhancement effect, which can directly split the surface periodic structures of LSFL. Such new sub-sequent high spatial frequency LIPSS (HSFL) fabrication process is quite different from the traditional multi-pulse induced HSFL and can be used to fabricate large-area HSFL structures.
关键词： Nano-fabrication,Femtosecond laser,LIPSS,Chalcogenide glasses
更新于2025-09-11 14:15:04
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Ultrafast Broadband Diagnostics of the Filling of the s Band at the Two-Photon Femtosecond Laser Excitation of a Gold Film
摘要： The transmission of near infrared femtosecond laser pulses (wavelength of 800 nm) and supercontinuum radiation (300–750 nm) generated by them through a 50-nm gold film immersed in water has been experimentally studied at the power of focused laser radiation in the range of 1–10 GW. An increase in the excitation intensity is accompanied by the blueshift of the edge of the extinction band of the film, which is attributed to the filling of electronic states of the s band with a low density of states caused by two-photon interband transitions from d bands with a high density of states.
关键词： supercontinuum radiation,gold film,ultrafast broadband diagnostics,s band filling,two-photon femtosecond laser excitation
更新于2025-09-11 14:15:04
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Rapid anterior capsule contraction after femtosecond laser–assisted cataract surgery in a patient with retinitis pigmentosa
摘要： We report a case of rapid and extreme capsule contraction after uneventful femtosecond laser–assisted cataract surgery (FLACS) in one eye performed subsequent to uneventful standard phacoemulsification with manual continuous curvilinear capsulorhexis (CCC) creation in the fellow eye. In the setting of retinitis pigmentosa, the rapid and extreme anterior capsule contraction in the FLACS eye compared with the manual CCC eye might have been the result of release of inflammatory mediators from cell death during the laser capsulotomy combined with a structurally weaker CCC edge.
关键词： manual continuous curvilinear capsulorhexis,capsule contraction,femtosecond laser–assisted cataract surgery,retinitis pigmentosa
更新于2025-09-11 14:15:04
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Using a Polarization-Skewed Femtosecond Laser Pulse
摘要： We experimentally observe the bond stretching time of one-photon and net-two-photon dissociation pathways of singly ionized H2 molecules driven by a polarization-skewed femtosecond laser pulse. By measuring the angular distributions of the ejected photoelectron and nuclear fragments in coincidence, the cycle-changing polarization of the laser field enables us to clock the photon-ionization starting time and photon-dissociation stopping time, analogous to a stopwatch. After the single ionization of H2, our results show that the produced H+2 takes almost the same time in the one-photon and net-two-photon dissociation pathways to stretch to the internuclear distance of the one-photon coupled dipole-transition between the ground and excited electronic states. The spatiotemporal mapping character of the polarization-skewed laser field provides us a straightforward route to clock the ultrafast dynamics of molecules with sub-optical-cycle time resolution.
关键词： femtosecond laser pulse,H2 molecules,bond stretching time,sub-optical-cycle time resolution,dissociative ionization
更新于2025-09-11 14:15:04
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Small-Incision Femtosecond Laser–Assisted Intracorneal Concave Lenticule Implantation in Patients With Keratoconus
摘要： To evaluate the feasibility and efficacy of small-incision femtosecond laser–assisted intracorneal concave lenticule implantation (SFII) and penetrating keratoplasty (PKP) in patients with progressive keratoconus.
关键词： penetrating keratoplasty,femtosecond laser,keratoconus,intracorneal implantation,small incision
更新于2025-09-11 14:15:04
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Three-Year Outcome Comparison Between Femtosecond Laser-Assisted and Manual Descemet Membrane Endothelial Keratoplasty
摘要： To evaluate 3-year outcomes of femtosecond laser-assisted Descemet membrane endothelial keratoplasty (F-DMEK) compared with manual Descemet membrane endothelial keratoplasty (M-DMEK) in patients with Fuchs endothelial corneal dystrophy (FECD). A retrospective, interventional study, including eyes with FECD and cataract that underwent either F-DMEK or M-DMEK combined with cataract extraction at either the Toronto Western Hospital or Kensington Eye Institute, and that had at least 18 months’ follow-up was conducted. Exclusion criteria: complicated anterior segments, previous vitrectomy, previous keratoplasty, corneal opacity, or any other visually signi?cant ocular comorbidity. Included were 16 eyes of 15 patients in the F-DMEK group (average follow-up 33.0 6 9.0 months) and 45 eyes of 40 patients in the M-DMEK group (average follow-up 32.0 6 7.0 months). There were no issues with the creation of femtosecond descemetorhexis (in the F-DMEK group)—all descemetorhexis cuts were complete. Best spectacle-corrected visual acuity improvement did not differ signi?cantly between the groups at 1, 2, and 3 years (P = 0.849, P = 0.465 and P = 0.936, respectively). Rates of signi?cant detachment in F-DMEK and M-DMEK were 1 of 16 eyes (6.25%) and 16 of 45 eyes (35.6%) (P = 0.027). Rebubbling rates were 1 of 16 eyes (6.25%) and 15 of 45 eyes (33.3%) (P = 0.047). Cell-loss rates following F-DMEK and M-DMEK were 26.8% and 36.5% at 1 year (P = 0.042), 30.5% and 42.3% at 2 years (P = 0.008), 37% and 47.5% at 3 years (P = 0.057), respectively. Graft failure rate was 0% in F-DMEK and 8.9% in M-DMEK (all were primary failures; P = 0.565). F-DMEK showed good ef?cacy with reduced detachment, rebubble, and cell-loss rates, compared with M-DMEK.
关键词： long-term,IEK,Fuchs dystrophy,femtosecond laser,descemetorhexis,Descemet membrane endothelial keratoplasty,DMEK
更新于2025-09-11 14:15:04