A solar-pumped laser (or solar-powered laser) is a

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

that shares the same

optical Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultravio ...

properties as conventional lasers such as emitting a beam consisting of

coherent Coherence is, in general, a state or situation in which all the parts or ideas fit together well so that they form a united whole. More specifically, coherence, coherency, or coherent may refer to the following: Physics * Coherence (physics ...

electromagnetic In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interacti ...

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes: * ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...

which can reach high power, but which uses

solar radiation Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible light perceptible to the human eye as well as invisible infrared (typically p ...

for pumping the

lasing medium The active laser medium (also called a gain medium or lasing medium) is the source of optical gain within a laser. The gain results from the stimulated emission of photons through electronic or molecular transitions to a lower energy state from ...

. This type of laser is unique from other types in that it does not require any artificial energy source.

Lasing media

The two most studied lasing media for solar-pumped lasers have been

iodine Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...

,De Young et al. Preliminary Design and Cost of a 1-Megawatt Solar-Pumped Iodide Laser Space-to-Space Transmission Station, NASA Technical Memorandum, 1987
Original versionWebCite archive
, Retrieved 2011-06-23 with a laser wavelength of 1.31 micrometers, and NdCrYAG, which lases at 1.06 micrometers wavelength. Solar-pumped semiconductor lasers have also been proposed by Landis and others.

Applications

Solar-pumped lasers are not used commercially because the low cost of electricity in most locations means that other more efficient types of lasers that run on electrical power can be more economically used. Solar pumped lasers might become useful in off-grid locations.

Nanopowders

Very fine grained dispersed powders can be produced by the use of laser synthesis technology.

Hydrogen production

A leader in this field is Shigeaki Uchida and his team in Japan (Tokyo/Osaka). Their design uses

Fresnel lens A Fresnel lens ( ; ; or ) is a type of composite compact lens (optics), lens which reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections. The simpler Dioptrics, d ...

es and a solar-pumped NdCrYAG laser to drive a magnesium-based cycle, which produces hydrogen gas as its product.

Potential spacecraft applications

Since there is no 'grid' power in space, most spacecraft today use solar power sources, mostly

photovoltaic Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commercially ...

solar cells. Powering lasers requires high levels of power, so the inefficiency of PV solar cells (usually less than 27% efficiency) motivates interest in solar pumping of lasers. Other potential benefits of solar-pumped lasers might be reduced weight and reduced number of components, affording higher reliability (reduced number of failure modes) versus an electrically pumped laser powered from PV cells. They can also be used for deep space communications, sensors for conditions on earth, detecting and tracking objects in space, as well as power transmission.

Solar-energy conversion

There have been proposals to use solar-pumped laser for solar-energy conversion, shown how to efficiently convert solar into electrical energy, taking advantage of laser amplification and intra-cavity use of a low-efficiency converter such as PV cells.

Current research

A proposal to use the solar furnace of Uzbekistan to power a solar-pumped Nd:YAG laser would have been the world's largest system of its kind, at up to 1 MW of solar input power. However, current research efforts are focused on combining the output from several smaller concentrators, an approach that is much more achievable.

References

{{Solid-state laser Directed-energy weapons Military lasers Laser types