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过滤筛选
- 2020
- fast processes in solids
- femtosecond interferometry
- femtosecond laser radiation
- Optoelectronic Information Science and Engineering
- Prokhorov General Physics Institute, Russian Academy of Sciences; National Research Nuclear University MEPhI
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Live E. coli bacteria label-free sensing using a microcavity in-line Mach-Zehnder interferometer
摘要： The paper presents the first study to date on selective label-free biosensing with a microcavity in-line Mach-Zehnder interferometer induced in an optical fiber. The sensing structures were fabricated in a single-mode fiber by femtosecond laser micromachining. In contrast to other studies of this sensing scheme, where only the sensitivity to refractive index changes in the cavity was investigated, this research used chemical surface treatment of the sensor to ensure detection specificity. Immobilized MS2 bacteriophages were applied as recognition elements specifically targeting live E. coli C3000 bacteria. It is shown that the sensor allows for real-time monitoring of biological phenomena taking place on the surface of the microcavity. The developed biosensor exhibits ultrahigh refractive index sensitivity of 15,000 nm/RIU and is capable of detecting live E. coli bacteria concentrations as low as 100 colony forming units (CFU)/mL in liquid volume as low as picoliters.
关键词： label-free biosensing,E. coli C3000 bacteria,refractive index sensitivity,MS2 bacteriophages,femtosecond laser micromachining,microcavity in-line Mach-Zehnder interferometer,optical fiber
更新于2025-09-23 15:21:21
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Point-by-Point Femtosecond-Laser Inscription of 2-μm-Wavelength-Band FBG through Fiber Coating
摘要： We propose a point-by-point inscription method for fiber Bragg grating (FBG) fabrication using a femtosecond pulsed laser focused through a fiber polyimide coating, realizing a 2-μm-wavelength-band FBG. A femtosecond laser acts as the inscription laser, focused by a 63× oil lens. A first-order FBG was fabricated with a grating interval of 700 nm. The 15- μW pulsed laser was focused directly on the fiber core through the polyimide coating and cladding. A first-order FBG for 2004.8-nm light with more than 56% reflectances was fabricated. High wavelength sensitivity and linearity of the FBG were demonstrated by temperature and strain-sensing testing. The first-order FBG of 2004.8 and 2000.2 nm resonant wavelengths could be realized simultaneously through parallel inscription method in 3000μm long grating area.
关键词： 2-μm-wavelength-band,Fiber Bragg grating,Erbium-doped fiber laser,Femtosecond pulsed laser
更新于2025-09-23 15:21:21
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Atomic simulation of irradiation of Cu film using femtosecond laser with different pulse durations
摘要： It is necessary to understand the light-matter interaction for application of femtosecond laser micro/nanoprocessing. In this work, the authors investigated the melting and disintegration behavior of a Cu film irradiated by a femtosecond laser with different pulse durations in the range of 35–500 fs by using a combined two temperature model (TTM) and molecular dynamics (MD) method. On the basis of TTM-MD, the temperature and stress evolution of the Cu film were analyzed. The result indicated that the Cu film disintegrates when the pulse duration is shorter than 100 fs but melts at a pulse duration of 200 fs. The photomechanical and thermomechanical evolutions induced by the femtosecond laser were also analyzed. The stress wave and increasing temperature were the main reasons for film disintegration and vibration. The snapshots of the Cu film indicate the melting and disintegration processes on an atomic scale. It shows that the melting occurs homogeneously, whereas the disintegration occurs at the center of the film. These results are helpful to understand the mechanism of femtosecond laser materials ablation.
关键词： TTM-MD simulation,Cu film,pulse durations,femtosecond laser,irradiation
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE International Electron Devices Meeting (IEDM) - San Francisco, CA, USA (2019.12.7-2019.12.11)] 2019 IEEE International Electron Devices Meeting (IEDM) - Demonstration of BEOL-compatible ferroelectric Hf <sub/>0.5</sub> Zr <sub/>0.5</sub> O <sub/>2</sub> scaled FeRAM co-integrated with 130nm CMOS for embedded NVM applications
摘要： We present a phase mask inscription technique with two beam interferometry using a lateral nonhomogeneous beam splitter to create gratings with nonhomogeneous periods, the so-called chirped fiber Bragg gratings. Inscription experiments with deep ultraviolet excimer and femtosecond laser sources reveal how this inscription method depends on the coherence properties of the inscription laser. Nonhomogeneous beam splitters are shown to provide a method to generate chirped fiber Bragg gratings with great wavelength versatility, even with the ultraviolet femtosecond laser.
关键词： Femtosecond laser,optical fiber filters,two-beam interferometry,fiber Bragg gratings
更新于2025-09-23 15:21:01
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Tm-doped all-fiber structured femtosecond laser mode-locked by a novel Chem-Te saturable absorber
摘要： We succeed in developing a chemically synthesized tellurium nanocrystals (Chem-Te) thin film by liquid phase peeling technique, and demonstrate this material is an effective saturable absorber (SA) for realization of stable mode-locking in an all-fiber structured thulium-doped laser cavity. By integrating this SA into an all-fiber structured ring laser cavity, we obtained the mode-locked pulses at the repetition rate of 11.17 MHz, the achieved pulses spectral bandwidth FWHM (full width at half maximum) of 5.26 nm and the pulses duration of 890 fs with 620 mW pump power at 1560 nm, the fundamental mode-locked laser output power as high as 5.35 mW. In addition, by further increasing the pump power, the second-order and third-order harmonic mode-locked pulses train of this fiber laser were also observed. To the best of our knowledge, this is the first report on the novel Chem-Te material saturable absorption property realization in 2 μm-band fiber laser system.
关键词： Femtosecond laser,Saturable absorber,Chem-Te,Mode-locked
更新于2025-09-23 15:21:01
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Neue Intraokularlinsendesigns f??r die Femtosekundenlaser-assistierte Kataraktoperation; New intraocular lens designs for femtosecond laser-assisted cataract operations;
摘要： The perfection and high reproducibility of capsulotomy in femtosecond laser-assisted cataract surgery (FLACS) lead to the possibility of new intraocular lens (IOL) designs for capsulotomy fixed implantation. Currently four different types of femtolenses for capsulotomy fixation are described in the literature or are commercially available. The first described was the lens in the bag or Tassignon IOL, which was developed for secondary cataract prevention, the second was the Masket IOL for reduction of negative dysphotopsia and third the 90F designed by Dick. All three types are or will be produced by Morcher. The fourth lens is the Femtis from Oculentis. All lenses are characterized by a high level of safety during implantation, The Tassignon lens leads to reduction of secondary cataract, especially in juvenile cataract because of the additional posterior capsulotomy. In studies the Masket IOL could show a decrease of negative dysphotopsia. In comparison to standard lenses, the 90F and Femtis in particular showed better results with respect to tilt, rotation and decentration. The new IOL designs for capsulotomy fixation show a safe implantation procedure and indications for a very stable position in the capsular sac. Further studies must be carried out to confirm the possible advantages in comparison to standard IOL with respect to postoperative results for refraction, tilt, rotation and decentration and possible induction of aberrations.
关键词： Femtolens,Femtosecond laser-assisted cataract surgery,Capsulotomy,Decentration,Tilt
更新于2025-09-23 15:21:01
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Time-Resolved Impulsive Stimulated Raman Spectroscopy with Synchronized Triple Mode-Locked Lasers
摘要： A complete understanding of a photochemical reaction dynamics begins with real-time measurements of both electronic and vibrational structures of photoexcited molecules. Time-resolved impulsive stimulated Raman spectroscopy (TR-ISRS) with femtosecond actinic pump, Raman pump, and Raman probe pulses is one of the incisive techniques enabling one to investigate the structural changes of photoexcited molecules. Here, we demonstrate that such femtosecond TR-ISRS is feasible with synchronized triple mode-locked lasers without using any time-delay devices. Taking advantage of precise control of the three repetition rates independently, we could achieve automatic scanning of two delay times between the three pulses, which makes both rapid data acquisition and wide dynamic range measurement of the fifth-order TR-ISRS signal achievable. We thus anticipate that the present triple mode-locked laser-based TR-ISRS technique will be of critical use for long-term monitoring of photochemical reaction dynamics in condensed phases and biological systems.
关键词： pump-dump-probe,fifth-order electronic spectroscopy,impulsive stimulated Raman spectroscopy,femtosecond Raman scattering,Time-resolved vibrational spectroscopy
更新于2025-09-23 15:21:01
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Intercellular Trafficking of Gold Nanostars in Uveal Melanoma Cells for Plasmonic Photothermal Therapy
摘要： Efficient plasmonic photothermal therapies (PPTTs) using non-harmful pulse laser irradiation at the near-infrared (NIR) are a highly sought goal in nanomedicine. These therapies rely on the use of plasmonic nanostructures to kill cancer cells while minimizing the applied laser power density. Cancer cells have an unsettled capacity to uptake, retain, release, and re-uptake gold nanoparticles, thus offering enormous versatility for research. In this work, we have studied such cell capabilities for nanoparticle trafficking and its impact on the effect of photothermal treatments. As our model system, we chose uveal (eye) melanoma cells, since laser-assisted eye surgery is routinely used to treat glaucoma and cataracts, or vision correction in refractive surgery. As nanostructure, we selected gold nanostars (Au NSs) due to their high photothermal efficiency at the near-infrared (NIR) region of the electromagnetic spectrum. We first investigated the photothermal effect on the basis of the dilution of Au NSs induced by cell division. Using this approach, we obtained high PPTT efficiency after several cell division cycles at an initial low Au NS concentration (pM regime). Subsequently, we evaluated the photothermal effect on account of cell division upon mixing Au NS-loaded and non-loaded cells. Upon such mixing, we observed trafficking of Au NSs between loaded and non-loaded cells, thus achieving effective PPTT after several division cycles under low irradiation conditions (below the maximum permissible exposure threshold of skin). Our study reveals the ability of uveal melanoma cells to release and re-uptake Au NSs that maintain their plasmonic photothermal properties throughout several cell division cycles and re-uptake. This approach may be readily extrapolated to real tissue and even to treat in situ the eye tumor itself. We believe that our method can potentially be used as co-therapy to disperse plasmonic gold nanostructures across affected tissues, thus increasing the effectiveness of classic PPTT.
关键词： nanoparticle endocytosis,femtosecond pulse laser,nanoparticle exocytosis,gold nanostars,plasmonic photothermal therapy
更新于2025-09-23 15:21:01
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Zircon fissiona??track and Ua??Pb double dating using femtosecond laser ablationa??inductively coupled plasmaa??mass spectrometry: A technical note
摘要： We present a new LA–ICP–MS system for zircon fission-track (FT) and U–Pb double dating, whereby a femtosecond laser combined with galvanometric optics simultaneously ablates multiple spots to measure average surface U contents. The U contents of zircon measured by LA–ICP–MS and standardized with the NIST SRM610 glass are comparable to those measured by the induced fission track method, and have smaller analytical errors. LA–ICP–MS FT dating of seven zircon samples including three IUGS age standards is as accurate as the external detector method, but can give a higher-precision age depending on the counting statistics of the U content measurement. Double dating of the IUGS age standards gives FT and U–Pb ages that are in agreement. A chip of the Nancy 91500 zircon has a homogeneous U content of 84 ppm, suggesting the possibility of using this zircon as a matrix-matched U standard for FT dating. When using the Nancy 91500 zircon as a U standard, a zeta calibration value of 42–43 yr cm?2 for LA–ICP–MS FT dating is obtained. While this value is strictly only valid for the particular session, it can serve as a reference for other studies.
关键词： dating,femtosecond laser,U–Pb,fission track,zircon,LA–ICP–MS
更新于2025-09-23 15:21:01
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THz Wave Emission From ZnTe Nano-Colloidal Aqueous Dispersion Irradiated by Femtosecond Laser
摘要： THz wave emission from ZnTe nano-colloidal aqueous dispersion flow (the particle size is 5-nm in diameter, the flow thickness is 17 μm) with two different particle densities (1.60 mmol/L and 1.07 mmol/L) was measured by time-domain spectroscopy (TDS) under femtosecond laser irradiation (>35 fs/transform-limited, 800 nm, horizontally-polarized, 0.5 kHz) in air. Intensity increase and peak shift in the TDS signal wave-form if compared with distilled water indicate that THz wave emission is induced in ZnTe nano-particles in the aqueous dispersion.
关键词： Terahertz,femtosecond laser,ZnTe nano-colloid
更新于2025-09-23 15:21:01