History of Lasers

... when the first lasers were operated, I and other scientists close to the research were surprised at how easy it turned out to be. We had assumed that, since lasers had never been made, it must be very difficult. But once you knew how, it was not at all difficult. Mostly what had been lacking were ideas and concepts.
- Arthur L Schawlow, 1981 Nobel Prize for Laser Spectroscopy (Talbot)

Picture of Einstein from: http://home.achilles.net/~jtalbot/history/einstein.html

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)

Picture of Bose from http://home.achilles.net/~jtalbot/history/einstein.html

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) Picture from: http://home.achilles.net/~jtalbot/history/ammonia.html

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)  Picture from: http://home.achilles.net/~jtalbot/history/ruby.html

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:

Picture from: http://home.achilles.net/~jtalbot/history/ruby.html

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:


Picture from: http://home.achilles.net/~jtalbot/history/gasdynamic.html

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