Light Amplification by Stimulated Emission of Radiation

Laser science or laser physics is a branch of

optics 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, ultra ...

that describes the theory and practice of

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 firs ...

s. Laser science is principally concerned with quantum electronics,

laser construction A laser is constructed from three principal parts: *An energy source (usually referred to as the ''pump'' or ''pump source''), *A ''gain medium'' or ''laser medium'', and *Two or more mirrors that form an ''optical resonator''. Pump source The ...

optical cavity An optical cavity, resonating cavity or optical resonator is an arrangement of mirrors or other optical elements that forms a cavity resonator for light waves. Optical cavities are a major component of lasers, surrounding the gain medium and pro ...

design, the physics of producing a population inversion in laser media, and the temporal evolution of the light field in the laser. It is also concerned with the physics of laser beam propagation, particularly the physics of

Gaussian beam In optics, a Gaussian beam is a beam of electromagnetic radiation with high monochromaticity whose amplitude envelope in the transverse plane is given by a Gaussian function; this also implies a Gaussian intensity (irradiance) profile. Thi ...

s, with

laser applications Many scientific, military, medical and commercial laser applications have been developed since the invention of the laser in 1958. The coherency, high monochromaticity, and ability to reach extremely high powers are all properties which allow ...

, and with associated fields such as

nonlinear optics Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in ''nonlinear media'', that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typic ...

and

quantum optics Quantum optics is a branch of atomic, molecular, and optical physics dealing with how individual quanta of light, known as photons, interact with atoms and molecules. It includes the study of the particle-like properties of photons. Photons have ...

History

Laser science predates the invention of the laser itself.

Albert Einstein Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theor ...

created the foundations for the laser and

maser A maser (, an acronym for microwave amplification by stimulated emission of radiation) is a device that produces coherent electromagnetic waves through amplification by stimulated emission. The first maser was built by Charles H. Townes, Jam ...

in 1917, via a paper in which he re-derived

Max Planck Max Karl Ernst Ludwig Planck (, ; 23 April 1858 – 4 October 1947) was a German theoretical physicist whose discovery of energy quanta won him the Nobel Prize in Physics in 1918. Planck made many substantial contributions to theoretical ...

’s law of radiation using a formalism based on probability coefficients ( Einstein coefficients) for the absorption, spontaneous emission, and

stimulated emission Stimulated emission is the process by which an incoming photon of a specific frequency can interact with an excited atomic electron (or other excited molecular state), causing it to drop to a lower energy level. The liberated energy transfers to th ...

of electromagnetic radiation. The existence of stimulated emission was confirmed in 1928 by Rudolf W. Ladenburg.Steen, W. M. "Laser Materials Processing", 2nd Ed. 1998. In 1939, Valentin A. Fabrikant made the earliest laser proposal. He specified the conditions required for light amplification using stimulated emission. In 1947, Willis E. Lamb and R. C. Retherford found apparent stimulated emission in hydrogen spectra and effected the first demonstration of stimulated emission; in 1950, Alfred Kastler (Nobel Prize for Physics 1966) proposed the method of

optical pumping Optical pumping is a process in which light is used to raise (or "pump") electrons from a lower energy level in an atom or molecule to a higher one. It is commonly used in laser construction to pump the active laser medium so as to achieve popul ...

, experimentally confirmed, two years later, by Brossel, Kastler, and Winter. The theoretical principles describing the operation of a microwave laser (a maser) were first described by

Nikolay Basov Nikolay Gennadiyevich Basov (russian: Никола́й Генна́диевич Ба́сов; 14 December 1922 – 1 July 2001) was a Soviet physicist and educator. For his fundamental work in the field of quantum electronics that led to the deve ...

and

Alexander Prokhorov Alexander Mikhailovich Prokhorov (born Alexander Michael Prochoroff, russian: Алекса́ндр Миха́йлович Про́хоров; 11 July 1916 – 8 January 2002) was an Australian-born Soviet-Russian physicist known ...

at the ''All-Union Conference on Radio Spectroscopy'' in May 1952. The first maser was built by Charles H. Townes,

James P. Gordon James Power Gordon (March 20, 1928 – June 21, 2013) was an American physicist known for his work in the fields of optics and quantum electronics. His contributions include the design, analysis and construction of the first maser in 1954 as ...

, and Herbert J. Zeiger in 1953. Townes, Basov and Prokhorov were awarded the

Nobel Prize in Physics ) , image = Nobel Prize.png , alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then " ...

in 1964 for their research in the field of stimulated emission. Arthur Ashkin, Gérard Mourou, and

Donna Strickland Donna Theo Strickland (born 27 May 1959) is a Canadian optical physicist and pioneer in the field of pulsed lasers. She was awarded the Nobel Prize in Physics in 2018, together with Gérard Mourou, for the practical implementation of chirped p ...

were awarded the Nobel Prize in Physics in 2018 for groundbreaking inventions in the field of laser physics. The first working laser (a pulsed ruby laser) was demonstrated on May 16, 1960, by Theodore Maiman at the Hughes Research Laboratories.

References

External links

A very detailed tutorial on lasers
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History

See also

References

External links