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Projeto de investigação
50w/m2 collection efficiency continuous-wave solar-pumped laser with a ring array concentrator
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Quasi-Gaussian Multibeam Solar Laser Station for a Megawatt Solar Furnace
Publication . Costa, Hugo; Almeida, Joana; Liang, Dawei; Tibúrcio, Bruno D.; Garcia, Dário; Catela, Miguel; Vistas, Cláudia Alexandra da Rocha; DF – Departamento de Física; CeFITec – Centro de Física e Investigação Tecnológica
An alternative multirod solar side-pumping concept for the production of multiple quasi-Gaussian beams is proposed. This scheme was based on the One-Megawatt solar furnace in Odeillo, France, which collected and concentrated the solar light into a multilayered pyramidal pumping cavity placed at the focal zone. Each layer was comprised of a square array of four laser heads, each composed of a biconic surface that reflected the solar rays towards a Nd:YAG rod fixed inside a fused silica flow tube. A pyramidal reflector was placed inside the pumping cavity to close it and maximize the harness of solar energy. Compared to the previous multibeam solar laser station design for the same solar furnace, considerable alleviation of thermal lensing effects was achieved with the present approach, allowing the improvement of the laser beam quality factors and, consequently, the possibility of a 32-laser-beam generation, each with a quasi-Gaussian profile. For this case, 9.44 kW total laser power was calculated. Additionally, 20.01 kW total multimode laser power was numerically determined, which corresponds to a 10.93 W/m2 collection efficiency and a 2.0% solar-to-laser power conversion efficiency.
Seven-Rod Pumping Concept for Highly Stable Solar Laser Emission
Publication . Costa, Hugo; Liang, Dawei; Almeida, Joana; Catela, Miguel; Garcia, Dário; Tibúrcio, Bruno D.; Vistas, Cláudia R.; DF – Departamento de Física; CeFITec – Centro de Física e Investigação Tecnológica; MDPI - Multidisciplinary Digital Publishing Institute
A seven-rod solar laser head was conceptualized and numerically studied to improve the tracking error compensation capacity and power stability in end-side-pumping schemes. It was composed of a first-stage heliostat–parabolic mirror system, a second-stage fused silica aspheric lens and a third-stage conical pumping cavity, within which seven Nd:YAG rods were mounted. Highly stable solar laser emission, with a power loss inferior to 5% for tracking errors up to ±0.4°, could potentially be enabled with seven 4 mm diameter, 13 mm length rods. The tracking error width at 10% laser power loss was about 1.0°, which is 1.65 times higher than the experimental record, attained by a dual-rod side-pumping prototype. Furthermore, a total multimode laser power of about 41.2 W could also be achieved, corresponding to 23.3 W/m2 collection and 2.5% solar-to-laser power conversion efficiencies, which are 1.65 and 1.36 times higher than those obtained with the dual-rod side-pumping prototype. They are also 1.27 and 1.12 times higher than the multirod experimental records in multimode regime for the same rod material.
Uniform and Non-Uniform Pumping Effect on Ce:Nd:YAG Side-Pumped Solar Laser Output Performance
Publication . Vistas, Cláudia R.; Liang, Dawei; Garcia, Dário; Catela, Miguel; Tibúrcio, Bruno D.; Costa, Hugo; Guillot, Emmanuel; Almeida, Joana; CeFITec – Centro de Física e Investigação Tecnológica; DF – Departamento de Física; MDPI - Multidisciplinary Digital Publishing Institute
The Ce:Nd:YAG is a recent active medium in solar-pumped lasers with great potential. This study focuses on the influence of two secondary concentrators: a fused silica aspherical lens and a rectangular fused silica light guide; and consequent pump light distribution on the output performance of a Ce:Nd:YAG side-pumped solar laser. The solar laser head with the aspherical lens concentrated the incident pump light on the central region of the rod, producing the highest continuous-wave 1064 nm solar laser power of 19.6 W from the Ce:Nd:YAG medium. However, the non-uniformity of the absorbed pump profile produced by the aspherical lens led to the rod fracture because of the high thermal load, limiting the maximum laser power. Nevertheless, the solar laser head with the light guide uniformly spread the pump light along the laser rod, minimizing the thermal load issues and producing a maximum laser power of 17.4 W. Despite the slight decrease in laser power, the use of the light guide avoided the laser rod fracture, demonstrating its potential to scale to higher laser power. Therefore, the pumping distribution on the rod may play a fundamental role for Ce:Nd:YAG solar laser systems design.
Efficient Production of Doughnut-Shaped Ce:Nd:YAG Solar Laser Beam
Publication . Garcia, Dário; Liang, Dawei; Almeida, Joana; Catela, Miguel; Costa, Hugo; Tibúrcio, Bruno D.; Guillot, Emmanuel; Vistas, Cláudia R.; DF – Departamento de Física; CeFITec – Centro de Física e Investigação Tecnológica; Molecular Diversity Preservation International (MDPI)
Laser beams with a doughnut-shaped profile have garnered much attention for their contribution to trapping nanoparticles and improving the scanning speed during laser-based 3D metal printing. For this reason, the production of a doughnut-shaped solar laser beam by end-side pumping a Ce:Nd:YAG rod with a small reflective parabolic collector was investigated. The resultant beam profile shape depended on the absorbed solar power, displaying a TEM00-mode profile at elevated input power. This phenomenon was primarily attributed to the role of distributing energy around the central region of the crystal. In contrast, at lower input power, a doughnut-shaped beam emerged, characterized by minimal energy distribution at the center. Through experiments conducted with a collection area of 0.226 m2 and a nominal solar irradiance from 970 W/m2 to 1000 W/m2, it was demonstrated that sufficient energy was available to generate a doughnut-shaped beam with a solar laser collection efficiency of 5.96 W/m2, surpassing previous measurements by 1.32 times. Further research with a larger collection area of 0.332 m2 and a diverse solar irradiance range of 650 W/m2 to 800 W/m2 revealed that the presence of a thin layer of cloud caused a transition from a doughnut-shaped to a TEM10-mode and, eventually, a TEM00-mode as the absorbed input solar power increased. Notably, under heavier cloud cover, the laser beam exhibited deformation at low input power instead of maintaining a doughnut-shaped profile. This research significantly enhances our comprehension of doughnut-shaped solar laser beams and their reliance on solar energy. By harnessing the plentiful and readily accessible energy from the Sun, the incorporation of solar energy into the realm of solar-pumped lasers holds immense promise for promoting sustainability. This transformative utilization can progressively diminish the industry’s carbon footprint, yielding long-term environmental benefits.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
OE
Número da atribuição
PD/BD/142827/2018