Ytterbium-fiber Laser System Research Articles

Effect of surface modification on wettability and tribology by laser texturing in Al2O3.

The life of ceramic tools restricts the development of the manufacturing industry and can be increased through the enhancement of surface performance. Laser surface texturing is a feasible technology to improve ceramic tool life based on the relationship between surface properties and the laser-texturing process. In this study, ${{\rm Al}_2}{{\rm O}_3}$ substrates have been textured by an ytterbium fiber laser system with a wavelength of 1064 nm and a pulse duration of 50 ns. First, the damage threshold of ${{\rm Al}_2}{{\rm O}_3}$ was measured to provide a basis for selecting laser-texturing parameters. The surface morphology was characterized using a white confocal scanning microscope and a scanning electron microscope to investigate the characteristics of laser processing. Water contact angles were measured to investigate the relationship between laser parameters and changes in wettability. The surface energy of the superhydrophobic ceramic was calculated based on the contact angle. Combined X-ray photoelectron spectroscopy (XPS) measurement was used to explore the mechanism of wettability changes from the chemical component and microstructure perspectives. The friction coefficient of ${{\rm Al}_2}{{\rm O}_3}$ was determined by a ball-on-disc wear test. The results showed that laser texturing can significantly improve the surface hydrophobicity and friction stability.

Optimization of Ytterbium Laser Parameters for Texturing of Steel Surfaces

Laser surface texturing is used to improve the tribological properties of the sliding surface. Optimizing the laser parameters to get appropriate texture diameter and depth is one of the challenges for tribologist. In the present study, the effect of Ytterbium laser parameters on dimple depth and diameters is investigated. Steel samples with hardness 380HV and Young’s Modulus 200GPa are used. Surface texturing on steel sample surface is done by using an Ytterbium fiber laser system (iPG photonics), with a maximum laser power of 20W, wavelength of 1064nm, maximum frequency of 80 kHz. Input laser parameters (frequency, speed, power, and pulse) are varied to investigate its effect on dimple dimensions and finally optimized. An optical profilometer is used to measure the topography of laser textured samples. Based on the results, it has been found that with an increase in laser power; depth and diameter of dimples are increasing. Contrastingly with an increase in frequency and speed, depth of dimples keeps on decreasing. Variation in pulse length doesn’t show any significant change in dimple dimensions.

Single-mode millijoule fiber laser system with high pulse shaping ability

The coherent amplification network (CAN) aims at developing a laser system based on the coherent combination of multiple laser beams, which are produced through a network of high beam quality optical fiber amplifiers. For the front-end sources of high power laser facilities, single-mode linearly polarized beams in the nanosecond time scale are required. According to these two requirements, a millijoule polarized fiber laser system was studied. Using polarization maintaining Ytterbium-fiber laser system as the seed, 10-μm core diameter Yb-doped fiber amplifier as the first-stage power amplifier and 40-μm core diameter polarizing photonic crystal fiber (PCF) as the second-stage power amplifier, the all-fiber laser system output 1.06-mJ energy at 10 ns with diffraction limited mode quality. Using 85-μm core diameter rod-type PCF as the third-stage power amplifier, 2.5-mJ energy at 10-ns pulse width was obtained with better than 500:1 peak-to-foot pulse shaping ability and single-mode beam quality. The energy fluctuation of the system was 1.3% (rms) with 1-mJ output in an hour. This fiber laser system has the advantages of high beam quality, versatile pulse shaping ability, good stability, small volume, and free of maintenance, which can be used in many applications.

Coherent quasi-cw 153 nm light source at 33 MHz repetition rate

We present a quasi-cw laser in a vacuum ultraviolet region at megahertz repetition rate. The narrowband pulses generated from an ytterbium-fiber laser system at 33 MHz repetition rate at the central wavelength of 1074 nm are frequency-converted by successive stages of LiB(3)O(5) crystals and KBe(2)BO(3)F(2) crystals. The generated radiation at 153 nm has the shortest wavelength achieved through phase-matched frequency conversion processes in nonlinear optical crystals to our knowledge.

A Fiber-Laser Process for Cutting Thick Yttria-Stabilized Zirconia: Application and Modeling

A novel laser processing technique is demonstrated for cutting up to 13-mm-thick sections of Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic. Y-TZP is a high toughness engineering ceramic, which is extremely difficult to machine in its final state. However for some applications, this is nevertheless desirable. As an example, Y-TZP-based dentures represent an example of mass-customization in which it is essential to machine the required shape from solid billets rather than to produce customized molds. Typically this is done mechanically and necessitates the use of diamond-tipped grinding and drilling tools;, however, this process is very slow and suffers from problems of high tool wear. In this work, an Ytterbium fiber laser system has been used to achieve full thickness cuts via a novel controlled crack propagation technique at substantially greater thicknesses than previously possible. The build up of heat and stress in the material during the cutting process is analyzed in a finite-element model and compared with experimental data. This illustrates the mechanism by which cracks are driven in a controlled way to generate a cut. Processing rates are substantially faster than alternative cutting techniques available for this material with feed rates of up to 1.8 mm/s demonstrated.

Tunable, μs-pulsed ytterbium fiber laser system with a linewidth below 2.7 GHz

We report on a widely tunable, pulsed laser system with narrow spectral linewidth based on a continuous wave ytterbium fiber oscillator, a pulse shaper and a power amplifier stage. The system is tunable from 1055 nm to 1085 nm and provides a maximum pulse energy of 155 μJ with a pulse duration of 1–5 μs. The linewidth is less than 2.7 GHz over the whole tuning range.