Self-sweeping of laser wavelength and associated mode instabilities in fiber lasers

Aim of the study was to compare the cutting and coagulation properties of 1.56 and 1.94 μm fiber lasers with those of a 0.98 μm semiconductor laser.Materials and methods. A comparative study of the biological effects of 1.56 and 1.94 µm lasers and a 0.98 µm semiconductor laser used in a constant, continuous mode was carried out. The cutting properties of the lasers were evaluated on the chicken muscle tissue samples by the width and depth of the ablation zone formed via a linear laser incision at a speed of 2 mm/s, while the coagulation properties were assessed by the width of the lateral coagulation zone. The zones were measured using a surgical microscope and a calibration slide. For statistical analysis, power values of 3, 5, 7, 9, and 11 W were chosen for each laser wavelength.Results. Analysis of the findings confirmed that laser wavelength had a statistically significant effect on the linear dependence between incision parameters and laser power. It was found that the 1.56 μm fiber laser (water absorption) had a greater coagulation ability but a comparable cutting ability compared with the 0.98 μm laser (hemoglobin absorption). When used in the power mode of 7W or higher, the 1.94 µm laser provided superior cutting performance compared with the 0.98 µm semiconductor laser at the same exposure power. Elevating the power in any of the lasers primarily increased the width of the ablation zone, and to a lesser extent – the crater depth and the width of the lateral coagulation zone. Therefore, in comparison with the 0.98 μm semiconductor laser, higher radiation power in the 1.56 and 1.94 μm lasers mainly influences their cutting properties, expanding the width and depth of the ablation zone, and has a smaller effect on their coagulation ability.Conclusion. The findings of the study showed that the 1.56 and 1.94 μm fiber lasers have better coagulation properties in comparison with the 0.98 μm semiconductor laser. was statistically proven that all incision characteristics (width of the lateral coagulation zone, depth and width of the ablation zone) for the 1.56, 1.94, and 0.98 μm lasers depend on the power of laser radiation. The 1.94 µm laser is superior to the 0.98 µm laser in its cutting properties.

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Tailoring the output laser wavelength of fiber lasers by the intra-cavity inscription of LPFGs

Microwave and Optical Technology Letters ◽

10.1002/mop.29842 ◽

2016 ◽

Vol 58 (6) ◽

pp. 1430-1433

Author(s):

R.E. Nuñez-Gomez ◽

G. Anzueto-Sánchez ◽

A. Martínez-Rios ◽

I. Torres-Gomez ◽

J. Camas-Anzueto ◽

...

Keyword(s):

Fiber Lasers ◽

Laser Wavelength ◽

Output Laser

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High PowerTm3+-Doped Fiber Lasers Tuned by a Variable Reflective Output Coupler

Research Letters in Optics ◽

10.1155/2008/919403 ◽

2008 ◽

Vol 2008 ◽

pp. 1-3

Author(s):

Yulong Tang ◽

Yong Yang ◽

Jianqiu Xu

Keyword(s):

Output Power ◽

Output Coupler ◽

Fiber Lasers ◽

Tuning Range ◽

Maximum Output Power ◽

Laser Wavelength ◽

Output Coupling ◽

Maximum Output ◽

Diode Pumped ◽

Nm Range

Wide wavelength tuning by a variable reflective output coupler is demonstrated in high-power double-cladTm3+-doped silica fiber lasers diode-pumped at∼790 nm. Varying the output coupling from 96% to 5%, the laser wavelength is tuned over a range of 106 nm from 1949 to 2055 nm. The output power exceeds 20 W over 90-nm range and the maximum output power is 32 W at 1949 nm for 51-W launched pump power, corresponding to a slope efficiency of∼70%. Assisted with different fiber lengths, the tuning range is expanded to 240 nm from 1866 to 2107 nm with the output power larger than 10 W.

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The Effect of Laser Type and Power on the Efficiency of Industrial Cutting of Mild and Stainless Steels

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4031190 ◽

2015 ◽

Vol 138 (3) ◽

Cited By ~ 10

Author(s):

Jetro Pocorni ◽

Dirk Petring ◽

John Powell ◽

Eckard Deichsel ◽

Alexander F. H. Kaplan

Keyword(s):

Stainless Steels ◽

Laser Cutting ◽

Fiber Lasers ◽

Laser Energy ◽

Laser Wavelength ◽

Cutting Process ◽

Co2 Lasers ◽

Cutting Efficiency ◽

Thin Sections ◽

Material Thickness

This paper investigates the effect of material type, material thickness, laser wavelength, and laser power on the efficiency of the cutting process for industrial state-of-the-art cutting machines. The cutting efficiency is defined in its most basic terms: as the area of cut edge created per Joule of laser energy. This fundamental measure is useful in producing a direct comparison between the efficiency of fiber and CO2 lasers when cutting any material. It is well known that the efficiency of the laser cutting process generally reduces as the material thickness increases, because conductive losses from the cut zone are higher at the lower speeds associated with thicker section material. However, there is an efficiency dip at the thinnest sections. This paper explains this dip in terms of a change in laser–material interaction at high cutting speeds. Fiber lasers have a higher cutting efficiency at thin sections than their CO2 counterparts, but the efficiency of fiber laser cutting falls faster than that of CO2 lasers as the material thickness increases. This is the result of a number of factors including changes in cut zone absorptivity and kerf width. This paper presents phenomenological explanations for the relative cutting efficiencies of fiber lasers and CO2 lasers and the mechanisms affecting these efficiencies for stainless steels (cut with nitrogen) and mild steel (cut with oxygen or nitrogen) over a range of thicknesses. The paper involves a discussion of both theoretical and practical engineering issues.

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Imaging nanostructures on ablated kapton polymide

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150198 ◽

1993 ◽

Vol 51 ◽

pp. 872-873

Author(s):

Daniel L. Callahan ◽

H. M. Phillips ◽

R. Sauerbrey

Keyword(s):

Electron Microscopy ◽

Polymer Surface ◽

Grating Period ◽

Laser Wavelength ◽

Integrated Devices ◽

Transmission Electron ◽

Excimer Laser Irradiation ◽

Produce Line ◽

Line Patterns ◽

Anisotropic Conduction

Excimer laser irradiation has been used to interferometrically ablate submicron line patterns on to Kapton polyimide. Such patterned material may exhibit highly anisotropic conduction as was predicted from previous studies showing enhanced conductivity from uniformly ablated material. We are currently exploiting this phenomenon to create integrated devices using conventional polymers as both dielectrics and conductors. Extensive scanning electron microscopy (SEM) and limited transmission electron microscopy (TEM) have been conducted in order to characterize the morphology of such patterned nanostructures as a function of processing conditions.The ablation technique employed produces an interference pattern on the polymer surface of period equal to half that of a diffraction grating period, independent of the laser wavelength. In these experiments, a 328 nm grating has been used to produce line patterns of 164 nm line-spacings as shown in Figures 1 and 2. A 200 Å Au coating has been used to both prevent charging and, perhaps more importantly, enhance contrast.

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Linear and Nonlinear Optical Properties of Natural Dyes Freestanding Films and Application in Optical Limiting

10.32792/utq/utjsci/vol7/2/30 ◽

2020 ◽

pp. 139-143

Keyword(s):

Absorption Coefficient ◽

Water Solution ◽

Optical Limiting ◽

Refraction Index ◽

Laser Wavelength ◽

Solid State Laser ◽

Natural Dyes ◽

Linear And Nonlinear ◽

532 Nm ◽

Absorbance Spectra

Natural dyes were followed and prepared from a pomegranate, purple carrot, and eggplant peel. The absorbance spectra was measured in the wavelength range 300-800 nm. The linear properties measurements of the prepared natural dye freestanding films were determined include absorption coefficient (α0), extinction coefficient (κ), and linear refraction index (n). The nonlinear refractive index n2 and nonlinear absorption coefficient β2 of the natural dyes in the water solution were measured by the optical z-scan technique under a pumped solid state laser at a laser wavelength of 532 nm. The results indicated that the pomegranate dye can be promising candidates for optical limiting applications with significantly low optical limiting of 3.5 mW.

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