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" is an acronym for "light amplification by stimulated emission of radiation". The fir ...

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, ultraviole ...

properties as conventional lasers such as emitting a

beam Beam may refer to: Streams of particles or energy *Light beam, or beam of light, a directional projection of light energy **Laser beam *Particle beam, a stream of charged or neutral particles **Charged particle beam, a spatially localized grou ...

consisting of

coherent Coherence, coherency, or coherent may refer to the following: Physics * Coherence (physics), an ideal property of waves that enables stationary (i.e. temporally and spatially constant) interference * Coherence (units of measurement), a deri ...

electromagnetic In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions of a ...

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

which can reach high

power Power most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may a ...

, but which uses

solar radiation Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m ...

for pumping the

lasing medium The active laser medium (also called 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 a ...

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

hypothetical A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obser ...

megastructure A megastructure is a very large artificial object, although the limits of precisely how large vary considerably. Some apply the term to any especially large or tall building. Some sources define a megastructure as an enormous self-supporting a ...

called a stellaser which uses a star as both the power source ''and'' the lasing medium.

Lasing media

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

iodine Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions 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 The laser diode chip removed and placed on the eye of a needle for scale A laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with e ...

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 developed by the French physicist Augustin-Jean Fresnel (1788–1827) for use in lighthouses. It has been called "the invention that saved a million ships." The design allows the c ...

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 us ...

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.

Space propulsion

There have been proposals to use solar-pumped lasers for spacecraft

beam-powered propulsion Beam-powered propulsion, also known as directed energy propulsion, is a class of aircraft or spacecraft propulsion that uses energy beamed to the spacecraft from a remote power plant to provide energy. The beam is typically either a microwave or a ...

Solar power satellite

There have been proposals to use solar-pumped lasers for

space-based solar power Space-based solar power (SBSP, SSP) is the concept of collecting solar power in outer space by solar power satellites (SPS) and distributing it to Earth. Its advantages include a higher collection of energy due to the lack of reflection and ab ...

Current research

A proposal to use the

solar furnace of Uzbekistan The solar furnace of Uzbekistan was built in 1981, and is located 45 kilometers away from Tashkent city. The furnace is the largest in Asia. It uses a curved mirror, or an array of mirrors, acting as a parabolic reflector, which can reach temper ...

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