Continuous Wave Ytterbium Fiber Laser Research Articles

Features of synthesis of ZnSe ceramics from nanopowders obtained using a high-power laser

The reasons for the occurrence of optical inhomogeneities in ZnSe or Fe:ZnSe ceramics, which were made from nanoparticles, obtained using a continuous wave ytterbium fiber laser, were investigated. Evaporation of ZnSe at T ≤ 900 ˚С results in formation of large pores (0.5–10 µm) in the ceramics. When the material is oxidized by means of oxygen adsorbed from air onto the surface of nanoparticles, such refractory phases as ZnO and ZnSeO3 are formed. Even a low content of these phases (< 1 wt%) results in formation of accumulations of small crystallites (0.2–3 μm) in the ceramics. Numerous pores and extended accumulations of small crystallites are optical non-uniformities that scatter and absorb light. Changes in the chemical composition and contamination of ZnSe during the production of nanopowders and ceramics turned out to be too small for such inhomogeneities to form.

Thermomechanical response of aluminum alloys under the combined action of tensile loading and laser irradiations**Project supported by the National Natural Science Foundation of China (Grant No. 61605079) and the Fundamental Research Funds for the Central Universities, China (Grant No. 30916014112-020).

This study reports the investigation of the thermomechanical behavior of aluminum alloys (Al-1060, Al-6061, and Al-7075) under the combined action of tensile loading and laser irradiations. The continuous wave ytterbium fiber laser (wavelength 1080 nm) was employed as the irradiation source, while tensile loading was provided by the tensile testing machine. The effects of various pre-loading and laser power densities on the failure time, temperature distribution, and the deformation behavior of aluminum alloys are analyzed. The experimental results represent the significant reduction in failure time for higher laser power densities and for high preloading values, which implies that preloading may contribute a significant role in the failure of the material at elevated temperature. Fracture on a microscopic scale was predominantly ductile comprising micro-void nucleation, growth, and coalescence. The Al-1060 specimens behaved plastically to some extent, while Al-6061 and Al-7075 specimens experienced catastrophic failure. The reason and characterization of material failure by tensile and laser loading are explored in detail. A comparative behavior of under-tested materials is also investigated. This work suggests that studies considering only combined loading are not enough to fully understand the mechanical behavior of under-tested materials. For complete characterization, one should consider the effect of heating as well as loading rate and the corresponding involved processes with the help of thermomechanical coupling and the thermal elastic-plastic theory.

Laser-Induced Formation of Extended Modified Regions in Foam Glass Impregnated with Silver Salts

A method of writing extended modified regions with complex structure, which can act as waveguide microstructures in the interior of porous glass plates impregnated by solutions of silver salts, by means of 1.07 μm continuous-wave ytterbium fiber laser is examined. The results of studies of extended modified regions by optical methods are presented. Similar microstructures in the interior of glass can easily become base elements of fiber-optic systems for different applications.

Modification of electrical properties of TiO&lt;sub&gt;2&lt;/sub&gt; by continuous-wave ytterbium fiber laser irradiation

Modification of electrical properties of TiO&lt;sub&gt;2&lt;/sub&gt; by continuous-wave ytterbium fiber laser irradiation

Laser patterning of thermoelectric iron silicide on alumina substrates by continuous-wave ytterbium fiber laser irradiation

Laser patterning of thermoelectric iron silicide on alumina substrates by continuous-wave ytterbium fiber laser irradiation

Formation of modified areas of porous glass saturated with glycerin under the action of laser radiation

The formation of modified areas with changed optical properties in the volume of thin plates of porous glass (composition of 94.73SiO2 · 4.97B2O3 · 0.30Na2O), saturated with glycerin—a substance with a high polarization capacity, under the action of laser radiation was investigated. A continuous wave ytterbium fiber laser with radiation wavelength λ = 1.07 μm weakly absorbed by porous glass was used as the radiation source. When the radiation power was within the range of 9.6–16.5 W and the irradiation time was 270–300 s, optical-grade modified areas were obtained. During the experiment, the dependences of temperature in the spots of the impact and of the power of the radiation transmitted through a thin plate of porous glass, on irradiation time were registered.

Modification of electrical properties of zinc oxide by continuous wave ytterbium fiber laser irradiation

The polycrystalline plate-like ZnO samples were irradiated by a continuous wave Yb fiber laser and electrical properties of modified layer were investigated. The laser beam of spot size of 16 μm in diameter was scanned on the surface at a velocity of 5mm/s. There was a threshold for the laser modification. The laser etched grooves were formed above laser power of 20 W. The laser etched depth increased in relation to the laser power, 0.46 mm at 20 W and 5.0 mm at 126 W. The surface layers of laser etched grooves were modified in color and electrical property. The color changed from light yellow to black, and the electrical resistivity drastically decreased from initial value of 1.1×105 Ωcm to 3.2×10−1 Ωcm at 56 W, 2.8×10−1 Ωcm at 91 W, and 2.0×10−1 Ωcm at 126 W. The Hall measurement showed that the modified surface layer was an n-type semiconductor and carrier concentration of the layer was 1.5×1017 cm−3 at 56 W, 7.2×1017 cm−3 at 91 W, and 1.9×1018 cm−3 at 126 W.

Long wavelength extension of CW-pumped supercontinuum through soliton-dispersive wave interactions

A supercontinuum spanning over 700 nm with an average spectral power of 1.7 mW/nm and flatness of 6 dB was produced in a solid core, double zero dispersion wavelength photonic crystal fiber pumped with a high power, continuous-wave ytterbium fiber laser. The spectrum displays a strong feature centered around 1980 nm. Through numerical simulations we demonstrate that this feature is initially generated through the shedding of Cherenkov radiation by solitons at the second zero dispersion wavelength, and then extended by a four-wave mixing process between this generated dispersive component and other solitons forming the continuum.