scholarly journals Zigzag Multirod Laser Beam Merging Approach for Brighter TEM00-Mode Solar Laser Emission from a Megawatt Solar Furnace

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5437
Author(s):  
Hugo Costa ◽  
Joana Almeida ◽  
Dawei Liang ◽  
Miguel Catela ◽  
Dário Garcia ◽  
...  
Keyword(s):  
Laser Beam ◽  
Laser Power ◽  
Power Level ◽  
Fused Silica ◽  
Solar Furnace ◽  
Laser Beams ◽  
Output Power Level ◽  
Mode Laser ◽  
Tem00 Mode ◽  
Pump Cavity

An alternative multirod solar laser end-side-pumping concept, based on the megawatt solar furnace in France, is proposed to significantly improve the TEM00-mode solar laser output power level and its beam brightness through a novel zigzag beam merging technique. A solar flux homogenizer was used to deliver nearly the same pump power to multiple core-doped Nd:YAG laser rods within a water-cooled pump cavity through a fused silica window. Compared to the previous multibeam solar laser station concepts for the same solar furnace, the present approach can allow the production of high-power TEM00-mode solar laser beams with high beam brightness. An average of 1.06 W TEM00-mode laser power was numerically extracted from each of 1657 rods, resulting in a total of 1.8 kW. More importantly, by mounting 399 rods at a 30° angle of inclination and employing the beam merging technique, a maximum of 5.2 kW total TEM00-mode laser power was numerically extracted from 37 laser beams, averaging 141 W from each merged beam. The highest solar laser beam brightness figure of merit achieved was 148 W, corresponding to an improvement of 23 times in relation to the previous experimental record.

scholarly journals Doughnut-Shaped and Top Hat Solar Laser Beams Numerical Analysis

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7102
Author(s):  
Miguel Catela ◽  
Dawei Liang ◽  
Cláudia R. Vistas ◽  
Dário Garcia ◽  
Bruno D. Tibúrcio ◽  
...  
Keyword(s):  
Laser Beam ◽  
Laser Power ◽  
Mechanical Performance ◽  
Power Conversion ◽  
Fused Silica ◽  
Beam Profile ◽  
Mode Laser ◽  
Laser Beam Profile ◽  
Tem00 Mode ◽  
Conversion Efficiencies

Aside from the industry-standard Gaussian intensity profile, top hat and non-conventional laser beam shapes, such as doughnut-shaped profile, are ever more required. The top hat laser beam profile is well-known for uniformly irradiating the target material, significantly reducing the heat-affected zones, typical of Gaussian laser irradiation, whereas the doughnut-shaped laser beam has attracted much interest for its use in trapping particles at the nanoscale and improving mechanical performance during laser-based 3D metal printing. Solar-pumped lasers can be a cost-effective and more sustainable alternative to accomplish these useful laser beam distributions. The sunlight was collected and concentrated by six primary Fresnel lenses, six folding mirror collectors, further compressed with six secondary fused silica concentrators, and symmetrically distributed by six twisted light guides around a 5.5 mm diameter, 35 mm length Nd:YAG rod inside a cylindrical cavity. A top hat laser beam profile (Mx2 = 1.25, My2 = 1.00) was computed through both ZEMAX® and LASCAD® analysis, with 9.4 W/m2 TEM00 mode laser power collection and 0.99% solar-to-TEM00 mode power conversion efficiencies. By using a 5.8 mm laser rod diameter, a doughnut-shaped solar laser beam profile (Mx2 = 1.90, My2 = 1.00) was observed. The 9.8 W/m2 TEM00 mode laser power collection and 1.03% solar-to-TEM00 mode power conversion efficiencies were also attained, corresponding to an increase of 2.2 and 1.9 times, respectively, compared to the state-of-the-art experimental records. As far as we know, the first numerical simulation of doughnut-shaped and top hat solar laser beam profiles is reported here, significantly contributing to the understanding of the formation of such beam profiles.

Seven-rod pumping approach for the most efficient production of TEM00-mode solar laser power by a Fresnel lens

2021 ◽  
pp. 1-28
Author(s):  
Dawei Liang ◽  
Joana Alameda ◽  
Bruno Tibúrcio ◽  
Miguel Catela ◽  
Dario Garcia ◽  
...  
Keyword(s):  
Laser Power ◽  
Fresnel Lens ◽  
Fused Silica ◽  
Laser Resonator ◽  
Radius Of Curvature ◽  
Efficient Production ◽  
Output Mirror ◽  
Tem00 Mode ◽  
Solar Pump ◽  
Pump Cavity

Abstract A seven-rod/seven-TEM00 mode beam Fresnel lens solar laser pumping approach is here proposed. The Fresnel lens with 4.0 m2 collection area was used as the primary solar concentrator to pump seven 2.5 mm diameter, 15 mm length Nd:YAG rods within a conical pump cavity through a secondary fused silica aspheric concentrator. Within the pump cavity, solar pump rays not completely absorbed by one of the seven rods were furtherly absorbed by other rods, ensuring hence a high absorption efficiency and avoiding the serious thermal lensing and thermal stress issues associated with classical large rod solar lasers. Seven individual plane-concave large-mode resonators were adopted to enable a good overlap between solar pump mode and TEM00 laser oscillating mode. By using both ZEMAX® and LASCAD® software, the maximum total TEM00 mode solar laser power of 54.65 W was numerically calculated by optimizing the radius parameter of the Fresnel lens, the diameter of the laser rod and the radius of curvature of the laser resonator output mirror. 13.66 W/m2 TEM00 mode solar laser collection efficiency and 1.44% solar power-to-TEM00 mode laser power conversion efficiency were calculated, representing substantial enhancements of 4.66 times and 4.38 times, respectively, as compared to previous experimental records of the TEM00 mode solar laser pumped through a Fresnel lens with 0.785 m2 collection area. The feasibility of TEM00 mode solar laser power delivery by hollow-core photonic crystal fibers was finally studied.

Renovating electrical power-to-TEM00 mode laser power conversion efficiency with four-lamp/four-rod pumping scheme

2021 ◽  
pp. 1-11
Author(s):  
Miguel Catela ◽  
Dawei Liang ◽  
Cláudia R. Vistas ◽  
Dário Garcia ◽  
Bruno D. Tibúrcio ◽  
...  
Keyword(s):  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Laser Power ◽  
Power Conversion ◽  
Electrical Power ◽  
Mode Laser ◽  
Tem00 Mode

scholarly journals Dual Laser Beam Processing of Semiconducting Thin Films by Excited State Absorption

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1256
Author(s):  
Christoph Wenisch ◽  
Sebastian Engel ◽  
Stephan Gräf ◽  
Frank A. Müller
Keyword(s):  
Zinc Oxide ◽  
Excited State ◽  
Laser Beam ◽  
Excited State Absorption ◽  
Fused Silica ◽  
Laser Beams ◽  
Nanosecond Laser ◽  
Pulse Delay ◽  
Single Beam ◽  
Dual Laser

We present a unique dual laser beam processing approach based on excited state absorption by structuring 200 nm thin zinc oxide films sputtered on fused silica substrates. The combination of two pulsed nanosecond-laser beams with different photon energies—one below and one above the zinc oxide band gap energy—allows for a precise, efficient, and homogeneous ablation of the films without substrate damage. Based on structuring experiments in dependence on laser wavelength, pulse fluence, and pulse delay of both laser beams, a detailed concept of energy transfer and excitation processes during irradiation was developed. It provides a comprehensive understanding of the thermal and electronic processes during ablation. To quantify the efficiency improvements of the dual-beam process compared to single-beam ablation, a simple efficiency model was developed.

scholarly journals Intensity Correlation Functions for 'Thermalised' TEMn0 Laser Beams

1986 ◽  
Vol 39 (4) ◽  
pp. 505
Author(s):  
R Hoare ◽  
R Mardling ◽  
GJ Troup
Keyword(s):  
Laser Beam ◽  
Correlation Functions ◽  
Single Mode ◽  
Laser Beams ◽  
Ground Glass ◽  
Intensity Correlation ◽  
Mode Laser ◽  
Single Mode Laser ◽  
Glass Disc ◽  
Useful Life

A well-stabilised, single mode laser beam will give zero intensity correlation. However, a laser beam may be 'thermalised' by shining it on a rotating ground glass disc, and then intensity correlation experiments will give nonzero results. We present here calculations of the intensity correlation functions of the TEMlO, TEM20, TEM30 and TEM40 Gaussian-Hermite beams. We were led to perform these calculations by the results of intensity correlation measurements on a laser with 'butted-on' mirrors nearing the end of its useful life.

An alternative approach to determine the spot-size of a multi-mode laser beam and its application to diode laser beams

Pramana ◽  
1999 ◽  
Vol 53 (2) ◽  
pp. 307-319 ◽  
Author(s):  
Rakesh Kapoor ◽  
PK Mukhopadhyay ◽  
Jogy George ◽  
SK Sharma
Keyword(s):  
Laser Beam ◽  
Diode Laser ◽  
Spot Size ◽  
Laser Beams ◽  
Mode Laser ◽  
Alternative Approach ◽  
Multi Mode

scholarly journals Laser Superficial Fusion of Gold Nanoparticles with PEEK Polymer for Cardiovascular Application

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 971
Author(s):  
Oktawian Bialas ◽  
Mateusz Lis ◽  
Anna Woźniak ◽  
Marcin Adamiak
Keyword(s):  
Particle Size ◽  
Laser Beam ◽  
Gold Particle ◽  
Laser Power ◽  
Biomedical Application ◽  
Parameters Optimization ◽  
Size Reduction ◽  
Particle Size Reduction ◽  
Nano Gold ◽  
Gold Particle Size

This paper analyses the possibility of obtaining surface-infused nano gold particles with the polyether ether ketone (PEEK) using picosecond laser treatment. To fuse particles into polymer, the raw surface of PEEK was sputtered with 99.99% Au and micromachined by an A-355 laser device for gold particle size reduction. Biomimetic pattern and parameters optimization were key properties of the design for biomedical application. The structures were investigated by employing surface topography in the presence of micron and sub-micron features. The energy of the laser beam stating the presence of polymer bond thermalisation with remelting due to high temperature was also taken into the account. The process was suited to avoid intensive surface modification that could compromise the mechanical properties of fragile cardiovascular devices. The initial material analysis was conducted by power–depth dependence using confocal microscopy. The evaluation of gold particle size reduction was performed with scanning electron microscopy (SEM), secondary electron (SE) and quadrant backscatter electron detector (QBSD) and energy dispersive spectroscopy (EDS) analysis. The visibility of the constituted coating was checked by a commercial grade X-ray that is commonly used in hospitals. Attempts to reduce deposited gold coating to the size of Au nanoparticles (Au NPs) and to fuse them into the groove using a laser beam have been successfully completed. The relationship between the laser power and the characteristics of the particles remaining in the laser irradiation area has been established. A significant increase in quantity was achieved using laser power with a minimum power of 15 mW. The obtained results allowed for the continuation of the pilot study for augmented research and material properties analysis.

scholarly journals Laser beam calibration for wood surface colour treatment

2021 ◽  
Author(s):  
M. Jurek ◽  
R. Wagnerová
Keyword(s):  
Laser Beam ◽  
Power Control ◽  
Wood Surface ◽  
Laser Power ◽  
Production Quality ◽  
Chemical Processes ◽  
Continuous Control ◽  
Calibration System ◽  
Laser Engraving ◽  
Wood Surfaces

AbstractLaser engraving of photographs on wood surfaces is a challenging task. To optimize the outcome and production quality it is necessary to control every aspect of the laser engraving process. Most of the production machines and technologies overall are mainly focused on laser power control. However, with other systems and deeper knowledge of the wood characteristics it is possible to achieve even better quality. This paper deals with enlarging the number of achievable shades of burned wood and its optimization. A calibration system was developed to control colour shades of engraved wood with a combination of laser power and optic focus. With this approach it is possible to widen achievable palette of engraved shades by continuous control of chemical processes of laser and wood interaction. The production is divided into wood burning and wood carbonization by variation of laser beam focus.

Pump Laser Automatic Signal Control for Erbium-Doped Fiber Amplifier Gain, Noise Figure, and Output Spectral Power

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
I. S. Amiri ◽  
Ahmed Nabih Zaki Rashed ◽  
P. Yupapin
Keyword(s):  
Noise Figure ◽  
Spectral Power ◽  
Power Level ◽  
Fiber Amplifier ◽  
Pump Laser ◽  
Output Power Level ◽  
Signal Control ◽  
Erbium Doped Fiber Amplifier ◽  
Erbium Doped ◽  
Amplifier Gain

AbstractThis paper has simulated the pump laser automatic signal control for erbium-doped fiber amplifier gain, noise figure, and output spectral power. Signal gain and noise figure are deeply studied in relation to laser pump power variations at operating pumping wavelengths of 980 nm and 1,480 nm for previous and proposed models. Similar to the study of the light signal to noise ratio, output power level and maximum Q factor are also simulated versus EDFA amplifier length at pumping power of 500 mW and different pumping wavelength by using the proposed model. The obtained results are better by using a pumping wavelength of 1,480 nm than a pumping wavelength of 980 nm. The optimum EDFA amplifier is 5 m, which gives better performance than other amplifier lengths.

scholarly journals A critical look at the prediction of the temperature field around a laser-induced melt pool on metallic substrates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yi Shu ◽  
Daniel Galles ◽  
Ottman A. Tertuliano ◽  
Brandon A. McWilliams ◽  
Nancy Yang ◽  
...  
Keyword(s):  
Laser Beam ◽  
Constant Velocity ◽  
Three Dimensional ◽  
Laser Beams ◽  
Poor Control ◽  
Metallic Substrates ◽  
Melt Pool ◽  
Mechanical Models ◽  
Transport Effects ◽  
Thermal Histories

AbstractThe study of microstructure evolution in additive manufacturing of metals would be aided by knowing the thermal history. Since temperature measurements beneath the surface are difficult, estimates are obtained from computational thermo-mechanical models calibrated against traces left in the sample revealed after etching, such as the trace of the melt pool boundary. Here we examine the question of how reliable thermal histories computed from a model that reproduces the melt pool trace are. To this end, we perform experiments in which one of two different laser beams moves with constant velocity and power over a substrate of 17-4PH SS or Ti-6Al-4V, with low enough power to avoid generating a keyhole. We find that thermal histories appear to be reliably computed provided that (a) the power density distribution of the laser beam over the substrate is well characterized, and (b) convective heat transport effects are accounted for. Poor control of the laser beam leads to potentially multiple three-dimensional melt pool shapes compatible with the melt pool trace, and therefore to multiple potential thermal histories. Ignoring convective effects leads to results that are inconsistent with experiments, even for the mild melt pools here.

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