- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Application of Femtosecond Laser in Anterior Segment Surgery
摘要： Femtosecond laser (FSL) is a near-infrared laser that can create reliable and reproducible tissue cutting with minimal damage to adjacent tissue. As the laser can also create incisions with various orientations, depths, and shapes, it is expected to be a useful tool for anterior segment surgery, such as cornea, refractive, and cataract surgery. In this review, the authors will introduce the application of FSL in various anterior segment surgeries and discuss the results of studies regarding the efficacy and safety of FSL in cornea, refractive, and cataract surgery. Experimental studies regarding the potential use of FSL will also be introduced. The studies discussed in this review suggest that FSL may be a useful tool for improving the prognosis and safety of surgeries of the anterior segment.
关键词： anterior segment surgery,Femtosecond laser,cataract surgery,refractive surgery,cornea surgery
更新于2025-09-23 15:19:57
-
A Simple Method for the Evaluation of the Pulse Width of an Ultraviolet Femtosecond Laser Used in Two-Photon Ionization Mass Spectrometry
摘要： A simple method was proposed for on-site evaluation of the pulse width of an ultraviolet femtosecond laser coupled with a mass spectrometer. This technique was based on measurement of a two-photon ionization signal in mass spectrometry by translation of the prism in the pulse compressor of the femtosecond laser. The method was applied to optical pulses that were emitted at wavelengths of 267, 241, and 219 nm; the latter two pulses were generated by four-wave Raman mixing using the third harmonic emission of a Ti:sapphire laser (267 nm) in hydrogen gas. The measurement results show that this approach is useful for evaluation of the pulse width of the ultraviolet femtosecond laser used in mass spectrometry for trace analysis of organic compounds.
关键词： pulse width,mass spectrometry,ultraviolet femtosecond laser,ionization
更新于2025-09-23 15:19:57
-
Femtosecond laser direct written off-axis fiber Bragg gratings for sensing applications
摘要： First order off-axis fiber Bragg gratings (FBGs) were fabricated in a standard single mode fiber (SMF-28e) through femtosecond laser direct writing. A minimum offset distance between the grating and core center of 2.5 μm was found to create a multimode section, which supports two separate fiber modes (LP0,1 and LP1,1), each split into two degenerate polarization modes. The resulting structure breaks the cylindrical symmetry of the fiber, introducing birefringence (≈10?4) resulting in a polarization dependent Bragg wavelength for each mode. Based on the modal and birefringence behavior, three off-axis FBGs were fabricated with 3.0, 4.5 and 6.0 μm offsets from the core center, and then characterized in strain, temperature, and curvature. The tested off-axis FBGs exhibited a similar strain sensitivity of ~1.14 pm/μ? and a temperature sensitivity of ~12 pm/C. The curvature and orientation angle were simultaneously monitored by analyzing the intensity fluctuation and the wavelength shift of the LP1,1 Bragg resonance. A maximum curvature sensitivity of 0.53 dB/m?1 was obtained for the off-axis FBG with a 3.0 μm offset.
关键词： optical fiber sensors,femtosecond laser direct writing,single mode fiber,off-axis fiber Bragg gratings,Birefringence
更新于2025-09-23 15:19:57
-
Improving Boston Type 1 Keratoprosthesis Procedure: One-Touch Femtosecond-Assisted Preparation and Centration of Donor Carrier Tissue
摘要： Purpose: We describe a technique to avoid decentration of the visual axis of the Boston type 1 keratoprosthesis (Kpro), performing 2 concentric trephinations with femtosecond laser. Methods: Two concentric side cuts were performed in a donor cornea using the 150-kHz Intralase? FS laser. Within the same applanation procedure, an 8.5-mm-diameter anterior side cut was performed, followed by a concentric 3-mm-diameter anterior side cut. Results: The technique was successfully replicated in 7 cases. Conclusions: Femtosecond laser-assisted double trephination results in a correctly prepared donor cornea, and in an inner side precisely matched with the prosthesis. At the end of the surgery, the Kpro was correctly centered.
关键词： Boston type 1,Femtosecond laser,Keratoprosthesis
更新于2025-09-19 17:15:36
-
RECENT ADVANCES IN ULTRAFAST TIME-RESOLVED SCANNING TUNNELING MICROSCOPY
摘要： Making smaller and faster functional devices has led to an increasing demand for a microscopic technique that allows the investigation of carrier and phonon dynamics with both high spatial and temporal resolutions. Traditional optical pump–probe methods can achieve femtosecond temporal resolution but fall short in the spatial resolution due to the diffraction limit. Scanning tunneling microscopy (STM), on the contrary, has realized atomic-scale spatial resolution relying on the high sensitivity of the tunneling current to the tip-sample distance. However, limited by the electronics bandwidth, STM can only push the temporal resolution to the microseconds scale, restricting its applications to probe various ultrafast dynamic processes. The combination of these two methods takes advantages of optical pump–probe techniques and highly localized tunneling currents of STM, providing one viable solution to track atomic-scale ultrafast dynamics in single molecules and low-dimensional materials. In this review, we will focus on several ultrafast time-resolved STM methods by coupling the tunneling junctions with pulsed electric waves, THz, near-infrared and visible laser. Their applications to probe the carrier dynamics, spin dynamics, and molecular motion will be highlighted. In the end, we will present an outlook on the challenges and new opportunities in this field.
关键词： terahertz technique,femtosecond laser,Scanning tunneling microscopy,pump-probe technique,ultrafast dynamics.
更新于2025-09-19 17:15:36
-
Surface behavior of 16Cr3Al ODS steel—Effects of high laser intensity 1014 W/cm2 in ambiences of air, helium and vacuum
摘要： The behavior of 16Cr3Al ODS steel (oxide dispersion strengthened steel), widely employed structural fusion material, under high-intensity laser radiation with intensity up to 1014 W/cm2 was investigated in air, helium and vacuum surrounding. Employed system was 65 fs laser at 804 nm, with applied pulse energy up to 5.25 mJ. Morphological effects were studied – cracking, crater parameters (depth, cross-section), LIPSS (laser-induced periodic surface structures) formation at the crater periphery, hydrodynamic effects, as well as chemical variations on the surface. Ablation thresholds were also determined for all three ambiences (for 100 applied pulses), and they were 0.30 J/cm2, 0.23 J/cm2 and 0.39 J/cm2 in air, helium and vacuum, respectively. Plasma occurred in all experiments and it was most prominent in vacuum due to strongest laser-material coupling.
关键词： 1014 W/cm2 laser intensity,Laser-induced damages/craters,Nuclear material,Femtosecond laser surface modification,ODS steel
更新于2025-09-19 17:13:59
-
Investigations on the laser cutting of LiNbO3
摘要： In this work, we study the precision cutting technology of LiNbO3 which is belonged to brittle materials and difficult to machine. By using a femtosecond laser, we explore the influence of wavelengths on the cutting quality, the surface and cross-section morphology of the specimens were examined by optical microscopy and have been measured. Subsequently, two optimization processing solutions have been designed to cut LiNbO3 with high quality and high reproducibility, the thermal effect and chipping have been reduced obviously. At last, the complete cut through the plate of LiNbO3 has been achieved.
关键词： LiNbO3,Thermal influence,Femtosecond laser,Laser cutting
更新于2025-09-19 17:13:59
-
Femtosecond laser induced step-like structures inside transparent hydrogel due to laser induced threshold reduction
摘要： In the area of laser material processing, versatile applications for cutting glasses and transparent polymers exist. However, parasitic effects such as the creation of step-like structures appear when laser cutting inside a transparent material. To date, these structures were only described empirically. This work establishes the physical and chemical mechanisms behind the observed effects and describes the influence of process and material parameters onto the creation of step-like structures in hydrogel, Dihydroxyethylmethacrylat (HEMA). By focusing laser pulses in HEMA, reduced pulse separation distance below 50 nm and rise in pulse energy enhances the creation of unintended step-like structures. Spatial resolved Raman-spectroscopy was used to measure the laser induced chemical modification, which results into a reduced breakdown threshold. The reduction in threshold influences the position of optical breakdown for the succeeding laser pulses and consequently leads to the step-like structures. Additionally, the experimental findings were supplemented with numerical simulations of the influence of reduced damage threshold onto the position of optical breakdown. In summary, chemical material change was defined as cause of the step-like structures. Furthermore, the parameters to avoid these structures were identified.
关键词： transparent hydrogel,laser induced threshold reduction,step-like structures,Raman-spectroscopy,femtosecond laser
更新于2025-09-19 17:13:59
-
Sub-micron structuring/texturing of diamond-like carbon-coated replication masters with a femtosecond laser
摘要： Diamond-like carbon (DLC) coatings have very attractive mechanical and tribological properties, i.e. high hardness, low friction and high wear resistance. Therefore, DLC is often used as a solid lubricant in moulds for injection moulding. Laser processing of DLC with ultrashort lasers, i.e. femtosecond lasers, can be performed both at micron and sub-micron scales, namely by producing laser-induced periodic surface structures (LIPSS). In this research, the effects of laser structuring/texturing on DLC properties are investigated. First, the laser-processing parameters were optimised to produce uniform LIPSS without damaging a thin DLC film and then the properties of the textured DLC-coated substrates were studied. It was determined that the tribological properties of the processed surfaces remained unchanged, but the hardness of the structured/textured DLC layers was reduced significantly. Although GAXRD and Raman spectroscopy did not show any significant crystallisation of the DLC coating after the laser irradiation, the analysis indicated that a thin graphitised layer had been formed on the surface as a result of the femtosecond laser processing.
关键词： Laser microprocessing,Femtosecond laser,LIPSS,Diamond-like carbon (DLC)
更新于2025-09-19 17:13:59
-
Wavelength-switchable erbium-doped fiber laser incorporating fiber Bragg grating array fabricated by infrared femtosecond laser inscription
摘要： Wavelength-switchable fiber laser systems have many potential applications. Herein, the use of an erbium-doped fiber laser based on parallel fiber Bragg gratings (FBGs) (ASE: amplified spontaneous emission; BRM: broadband reflection mirror; CCD: charged-coupled device; EDFL: erbium-doped fiber laser; FBG: fiber Bragg gratings; IR: infrared; MZI: Mach–Zehnder interferometer; OSA: optical spectrum analyzer; OC: output coupler; PC: polarization controller; SNR: signal-to-noise ratios; 3D: three-dimensional; wavelength division multiplexing (WDM)) is proposed to achieve C + L band triple-wavelength-switchable laser output at approximately 1.5 μm. In the proposed system configuration, three parallel FBGs with different resonant wavelengths were fabricated using an 800 nm femtosecond pulsed laser. The proposed fiber laser incorporates first-order FBGs with the periods of 538, 542, and 547 nm. The femtosecond laser was propagated through polyimide coating and cladding and was focused onto the fiber core by a 63× oil lens, while FBGs were inscribed with the use of a point-by-point method to generate resonant wavelengths at 1555.3, 1569.2, and 1583.1 nm. When the FBGs were used as wavelength selectors, a lasing threshold of 85 mW was obtained, and switchable lasing with stable single- and dual-wavelength outputs was achieved based on the adjustment of a polarization controller. Concerning the switchable single-wavelength lasing, the signal-to-noise ratio was greater than 37.23 dB, and the 3 dB linewidth was less than 0.09 nm. The respective power fluctuation measurements were less than 0.22 and 0.68 dB for the single- and dual-wavelength lasers at 26 °C over a scan time of 30 min.
关键词： Erbium-doped fiber laser,Femtosecond laser,Point-by-point wavelength generation method,Fiber Bragg grating
更新于2025-09-19 17:13:59