Miguel Catela

Universidade NOVA de Lisboa | NOVA · Department of Physics

Classical solar-pumped lasers often demand a significant amount of concentrated solar power for laser emission, which is only attainable under clear sky condition, limiting their applicability. In this research, we report the first solar laser emission at very low threshold solar power under cloudy sky condition by end-side-pumping a 2.5 mm diamete...

Solar laser technology typically requires a highly accurate solar tracking system that operate continuously, which increases energy consumption and reduces the system's lifetime. We propose a multi-rod solar laser pumping approach to enhance solar laser stability under non-continuous solar tracking conditions. Using a heliostat, solar radiation is...

It is reported here a large improvement in numerically calculated TEM00-mode side-pumped solar laser efficiency, and brightness figure-of-merit by pumping two thin Nd:YAG laser rods simultaneously with a ring-array solar energy primary concentrator. Two side-pumping configurations were investigated. A single-rod configuration was used to pump a typ...

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...

A multirod solar laser station for the megawatt solar furnace in Odeillo, France, was conceptualized and numerically studied to improve the solar-to-laser power conversion efficiency. 18 heliostats from the 63-heliostat field were selected, obtaining 347 kW of solar power at its focus. There, a two-dimensional compound parabolic concentrator furthe...

We report a significant numerical improvement in multi-rod laser efficiency, with an enhanced solar tracking error compensation capacity for a heliostat-parabolic system. The solar laser head was composed of a fused silica conical lens and a single conical pump cavity ensuring multiple passes through four 4.55 mm diameter, 15 mm length Nd:YAG rods....

We report here, to the best of our knowledge, the most efficient simultaneous emissions of three continuous-wave 1064 nm solar laser beams. A fused silica aspheric lens was used to couple the concentrated solar radiation from the focal zone of a 0.4 m 2 effective collection area primary parabolic mirror into three 2.5 mm diameter, 25 mm length 0.1a...

We present here the first experimental results of tracking error compensation capacity of a solar-pumped laser, with a largely enhanced tracking error tolerance achieved by pumping two laser rods simultaneously. A large aspherical fused silica lens, with an input face of 46 mm radius of curvature and 84 mm diameter, provided an efficient focusing o...

The efficiency potential of a small-size solar-pumped laser is studied here. The solar laser head was composed of a fused silica aspheric lens and a conical pump cavity, which coupled and redistributed the concentrated solar radiation from the focal zone of a parabolic mirror with an effective collection area of 0.293 m 2 to end-side pump a Ce(0.1...

We report here a significant enhancement in side-pumped solar laser collection efficiency and solar-to-laser conversion efficiency by a ring-array primary concentrator. A single and a dual-rod side-pumping configuration were numerically investigated. In the former, a thick laser rod was pumped with the full collection area of the ring-array solar c...

The solar laser power scaling potential of side-pumped Ce:Nd:YAG solar laser through a rectangular fused silica light guide was investigated by using a 2 m diameter parabolic con-centrator. The laser head was formed by the light guide and a V-shaped pump cavity to effi-ciently couple and redistribute the concentrated solar radiation from the parabo...

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 h...

A novel three-dimensional elliptical shape Fresnel lens (ESFL) analytical model is presented to evaluate and maximize the solar energy concentration of Fresnel-lens-based solar concentrators. AutoCAD, Zemax and Ansys software were used for the ESFL design, performance evaluation and temperature calculation, respectively. Contrary to the previous mo...

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, sol...

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 irradiate the target material, significantly reducing the heat affected zones, typical of Gaussian laser irradiation, whereas...

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 cor...

Lamp-pumped laser systems have been widely applied in research and industry. However, one of the major bottleneck issues in lamp-pumped laser development resides in its low electrical input-to-TEM00 mode laser conversion efficiency. Here is proposed a four-lamp/four-rod pumping concept to substantially increase electrical power to TEM00 mode laser...

The maximum achievable solar concentration of a single reflective primary parabolic mirror is limited by its physical aspect ratio. The maximum concentration of a single refractive Fresnel lens is also largely limited by its chromatic aberration. To resolve these shortcomings, a ring-array concentrator (RAC) analytical model with variable aspect ra...

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 a...

Economical, technological and demographic factors are hastening the already environmentally imperil global energy consumption. Governments and institutions urgently need to stimulate investment and research towards innovative approaches for efficiently produce energy with minimal harm to the delicate equilibrium of the terrestrial ecosystems. Semic...

A significant advancement in the Ce:Nd:YAG solar laser performance using a side-pumping configuration is reported here. A solar laser head was composed of a double-stage semispherical lens and a trapezoidal-shaped pumping cavity, which coupled and redistributed the concentrated solar radiation from the focal zone of a parabolic mirror into a laser...

Low lamp input-to-TEM00 mode laser output conversion efficiency and strong thermal lensing effects are bottleneck issues in commercially available single-rod/single-beam lamp-pumped lasers. A six-rod/six-beam concept is here proposed to substantially enhance lamp input-to-TEM00 mode laser output conversion efficiency. A 4 kW single thick arc lamp w...

A conversão directa de radiação solar em radiação laser tem ganho uma importância cada vez maior ao longo dos anos. Os lasers bombeados por luz solar fornecem soluções eficazes e ecológicas para a produção de radiação laser, tornando-se numa opção viável em locais com elevada irradiância solar e com poucas fontes de energia disponíveis. Um dos prin...

In present-day single-rod/single-beam solar laser systems, the thermal lens effect is a serious issue which limits its ability for a scale-up to higher powers and improved beam quality. Aiming at resolving this shortcoming, the concept of a seven-rod/seven-beam solar pumping scheme is proposed. This scheme was composed of a first stage heliostat-pa...

A multirod solar side-pumping concept is proposed to study the feasibility of multirod/multibeam laser systems in large-sized solar furnaces. This scheme was based on the one-megawatt solar furnace (MWSF) in Odeillo, France, which collected and concentrated solar rays into an input face of a solar homogenizer placed at the focal zone. At its output...

Laser emission based detection and imaging technology attract significant interest in biomedical research for its high sensitivity, narrow linewidth, and superior spectral and spatial resolution. Recent advances further revealed the potential to use laser emission to investigate chromatin dynamics, as well as to diagnose cancer tissues based on nuc...

In the 20 th century, the first quantum revolution allowed scientist to explore quantum effects and create disruptive technologies such as lasers, transistors and imaging, so widely applied and essential now days that they are unnoticeably fully integrated in almost every sector of human experience. Now scientist can unveil more and more of quantum...

To compare the penetration effect of both 1064 nm solar laser and concentrated solar radiations on biological tissue, ex vivo experiments were performed on chicken breast samples with similar incident doses. A 1064 nm Nd:YAG solar laser and a simple solar concentrator were firstly developed, both capable of emitting 10 W light power. Two square cro...