Lasers

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Laser history

Since boyhood Einstein wondered about light. He would wonder about its speed, and how it works. In fact most of Einstein's work involved light in someway or another. (Guillen) So of course when S.N.Bose sent Einstein a paper on light being a gas consisting of photons, Einstein was very interested. Bose's paper was more like a bunch of questions. For example he noticed that photons didn't behave like statistical billiard balls. Billiard balls that are shaken on a table will eventual fall in some pocket. But photons tended to fall in to one "pocket" if another photon was ready there. (Forward)

Einstein and Bose continued to work together on photons and noticed that one photon was indistinguishable from another photon. This let Einstein and Bose to conclude that strange behavior or photons was just statistical probability. (Forward)

For example if I have the set of numbers {1,2,3}   There are 6 subsets if each position is unique:
{1,2}   {1,3}    {2,3}
{2,1}   {3,1}    {3,2}

but if position doesn't matter then there are only 3 subsets:
{1,2} {2,3} {1,3}
Since {1,2} is the same as {2,1}

Using this idea and many other ideas Einstein laid the foundations for the laser by theorizing about the stimulated emission of radiation. His idea was that if you had a large number of atoms full of excess energy, and they were ready to emit a photon at some random time in some random direction, if a stray photon passed by, then the atoms are stimulated by its presence, and each atom may emit there photon early. This new photon would have the same direction and the same frequency as the original photon! Repeating this process with more and more photons each time is what gives us a lasers. (Forward)

Almost the first laser (a maser)

Einstein did not actual build the first laser. The first laser would not be created till 1954 by Townes. He called his invention a M.A.S.E.R. : Microwave Amplification by Stimulated Emission of Radiation. but skeptics read it as: Means of Acquiring Support for Expensive Research ! (Talbot) Townes first used Microwave energy to create resonance in ammonia, if the power input was really large, the ammonia would emit energy . Most people don't consider this a laser, since it was using Microwave energy to stimulate the atoms to change energy levels, but the maser did stimulate the research that lead to the laser.

The first laser (a pink ruby laser)

The first real laser was created in 1960 by Dr. T.H. Maiman. His L.A.S.E.R stood for Light Amplification by Stimulated Emission of Radiation. Notice that the Stimulated Emission of Radiation comes from the work of Einstein. You can see the first lasers were much smaller then the maser, but they would get very hot, so they had to be cooled by air, and would only operate in pulse mode, where the laser was primed by a flashing light. The laser it self was pretty simple, which surprised many people. Here is a diagram:

The Flash Tube is just like a flash on a camera, its job is to inject the photons in to the ruby. The ruby it self its the container of the atoms (the pockets of the billiard table in the example above) The ruby was polished and was coated with silver, with the emitter end of the ruby a little thinner, so some light could escape. The Quartz tube had the job of reflecting the photons to maximize the number of photons staying in the ruby. The trigger electrode is what raised the ruby to a higher potential. (Talbot)

All lasers work on this same basic principle where there is gas or solid that is excited and then lased with a photon and light is emitted. (howstuffworks) This light is highly symmetric and highly organized. It can also have quite a bit of energy with it. (LFI)

Lasers were quickly improved and by 1970 there were huge lasers like this gasdynamic laser:

This laser could pump out 135Kilowatts! Its hard to find information about lasers of this size since most of it is still classified. (Talbot)

Townes and Prokhorov were awarded the Nobel Science Prize in 1964 for their endeavours.

The Laser was a remarkable technical breakthrough, but in its early years it was something of a technology without a purpose. It was not powerful enough for use in the beam weapons envisioned by the military, and its usefulness for transmitting information through the atmosphere was severely hampered by its inability to penetrate clouds and rain. Almost immediately, though, some began to find uses for it. Maiman and his colleagues developed some of the first Laser weapons sighting systems and other engineers developed powerful lasers for use in surgery and other areas where a moderately powerful, pinpoint source of heat was needed.

History of the Development of the Laser

Date

Name

Achievement

1916
Albert Einstein Theory of light emission. Concept of Stimulated Emission.

1928
Rudolph W Landenburg Confirmed existence of stimulated emission and Negative Absorption.

1940
Valentin A Fabrikant Noted possibility of Population Inversion

1947

Willis E Lamb
R C Retherford
Induced Emission suspect in Hydrogen Spectra. First demonstration of stimulated emission.

1951
Charles H Townes The inventor of the MASER (Microwave Amplification of Stimulated Emission of Radiation) at Columbia University - First device based on stimulated emission, awarded Nobel prize 1964.

1951
Joseph Weber Independent inventor of MASER at University of Maryland.

1951
Alexander Prokhorov
Nikolai G Basov
Independent inventors of MASER at Lebedev Laboratories, Moscow. Awarded Nobel prize 1964

1954
Robert H Dicke "Optical Bomb" patent. Based on pulsed population inversion for superradiance and separately Fabry-Perot resonant chamber for "Molecular Amplification and Generation system".

1956
Nicolas Bloembergan First proposal for a three-level solid state MASER at Harvard University.

1957
Gordon Gould First document defining a LASER; notarised by a candy store owner. Credited with patent rights in the 1970s.

1958
Arthur L Schawlow
Charles H Townes
First detailed paper describing "Optical MASER". Credited with invention of LASER. From Columbia University.

1960
Arthur L Schawlow
Charles H Townes
LASER patent No. 2,929,922.

1960
Theodore Maiman Invented first working LASER based on Ruby. May 16th 1960, Hughes Research Laboratories.

1960
Peter P Sorokin
Mirek Stevenson
First Uranium LASER - Second LASER overall. Nov. 1960 IBM Labs.

1961
A G Fox and T Li Theoretical analysis of optical resonators at Bell Labs.

1961
Ali Javan
William Bennet Jr.
Donald Herriot
Invented Helium Neon (HeNe) LASER at Bell Labs.

1962
Robert Hall Invention of semi-conductor LASER at General Electric Labs.

1964
J E Geusic
H M Markos
L G Van Uiteit
Inventor of first working Nd:YAG LASER at Bell Labs.

1964
Kumar N Patel Inventor of CO2 LASER at Bell Labs.

1964
William Bridges Invention of Argon Ion LASER a Hughes Labs.

1965
George Pimentel
J V V Kasper
First chemical LASER at University of California, Berkley.

1966
William Silfvast
Grant Fowles and Hopkins
First metal vapour LASER - Zn/Cd - at University of Utah

1966
Peter Sorokin, John Lankard First Dye Laser action demonstrated at IBM Labs.

1969
G M Delco First industrial installation of three lasers for automobile application.

1970
Nikolai Basov's Group First Excimer LASER at Lebedev Labs, Moscow based on Xenon (Xe) only.

1974
J J Ewing and Charles Brau First rare gas halide excimer at Avco Everet Labs.

1977
John M J Madey's Group First free electron laser at Stanford University.

1980
Geoffrey Pert's Group First report of X-ray lasing action, Hull University, UK.

1981
Arthur Schawlow
Nicolas Bloembergen
Awarded Nobel Physics Prize for work in non-linear optics and spectroscopy.

1984
Dennis Matthew's Group First reported demonstration of a "laboratory" X-ray laser from Lawrence Livermore Labs.

In 1985 at the University of Rochester's Laboratory for Laser Energetics a breakthrough in creating ultrashort-pulse, very high-intensity (terawatts) laser pulses became available using a technique called chirped pulse amplification, or CPA, discovered by Gйrard Mourou. Later, in 1994, it was discovered by Mourou and his team at University of Michigan that the balance between the self-focusing refraction (see Kerr effect) and self-attenuating diffraction by ionization and rarefaction of a laser beam of terawatt intensities in the atmosphere creates "filaments" which act as waveguides for the beam thus preventing divergence. If a light filament drops below the intensity needed for this dynamic balance, called modulation instability, it can merge with another filament and continue propagating without broadening as with all earlier means of sending light. The filaments, having made a plasma, though turn the narrowband laser pulse into a broadband pulse having a wholly new set of applications.