History of the Laser

The primitive idea of the laser started in 1916, when Albert Einstein was studying the behavior of electrons inside the atom. Electrons are capable of absorbing or emitting light spontaneously. Einstein saw the possibility of stimulating the electrons coherently so that several of them could emit light with a certain wavelength. Although this was recognized as true, no one really thought of constructing a device that worked with this theory until the 50’s.

Laser means Light Amplification by Stimulated Emission of Radiation. Einstein discovered stimulated emission but, to construct a laser, that emission should be amplified. In 1951, the physicist Charles H. Townes discovered the necessary conditions to amplify the stimulated emission of microwaves. These waves are not visible light, but it was an essential step towards the laser. Three years later, Townes and Herbert Zeiger had constructed at the University of Columbia, New York, the first maser (Microwave Amplification by Stimulated Emission of Radiation). Investigators wanted to go further and started studying the same idea using other wavelengths, especially those of visible and infrared light.

In 1957, Townes and his friend and brother in law Arthur Schawlow started making progresses in the development of a maser that would emit visible light. At the same time, Gordon Gould, a graduate student at the Physics Department of Columbia (where Townes was professor) started to think about the same idea using for the first time the term laser. He stated that, with this device, it would be possible to reach energy densities much higher than expected. He also stated that a laser working at room temperature could generate a beam capable of melting steel.

At this moment a fight for the originality of the discovery started. In 1958, Townes and Schawlow presented the patents and sent a detailed report to the Physical Review. Gould, on the other hand, waited until 1959 and made the error of not sending any papers to any scientific journal. He abandoned eventually the university and started to work in a government defense project to study  possible military applications of the laser. This did not last long because of the  McCarthy’s “witch hunt”: he was accused of being a Marxist and was denied a direct intervention in his own project.

Until then it was believed that the best substances for developing a laser were gases, but then another physicist, Theodore Maiman, appeared in scene. Working at the Hughes Laboratories, in a aeronautic company , he started using ruby prisms. In 1960 he communicated that he had constructed a device that could emit laser light for a fraction of a second. The device was so simple and small that the public relations of Hughes preferred that the journalists photographed another device, much bigger, much complicated and impressive, but useless as a laser. The report was turned down by Physical Review Letters but was published by Nature. Very soon many laboratories around the world were able to prove Maiman’s discovery.

In 1964 Townes, Basov and Prokhorov won the Nobel price of physics. Townes got the patent of the maser which also included the laser. The specific patent for the laser was given to Townes and Schawlow. Maiman got the patent for his rubi laser.

Alejandro Pazó de la Sota