It is often challenging to link a technology or discovery to a single individual or instant in time, and the technology behind the laser is just one example. The laser was the result of not one individual’s efforts, but the combination of many leading optics and photonics scientists and engineers over the course of history.
The laser’s history can be traced back to 1900, when Max Plank published his work on the law of radiation, which explained the relationship between energy and the frequency of radiation, essentially saying that energy could be emitted or absorbed only in discrete chunks. His theory marked a turning point in physics and inspired Albert Einstein, who in 1905 released a paper on the photoelectric effect- which proposed that light also delivers its energy in chunks, now called photons. Taking these ideas further, in 1917 Einstein published the paper Zur Quantentheorie der Strahlung (On the Quantum Theory of Radiation). He described the theory of stimulated emission, establishing the underlining principle behind the maser and laser. Einstein theorized that, besides absorbing and emitting light spontaneously, electrons could be stimulated to emit light of a particular wavelength. It took over 30 years for scientists to prove his theory correct.
In the 1950’s scientists began work focused on harnessing energy by utilizing the principal of stimulated emission; most notable were scientists Charles Townes at Columbia University, and Alexander Prokhorov and Nikolai Basov at the Lebedev Laboratories in Moscow. In 1953, Townes produced the first maser (microwave amplification by stimulated emission of radiation), which was the first device developed based on Einstein’s theory and the precursor to the laser. In 1955, Basov and Prokhorov designed and built oscillators, and proposed a method for the production of negative absorption that was called the pumping method, which later became the main method of laser pumping.
In 1957, Charles Townes continued his work with the theory of stimulated emission and began to investigate visible light amplification. Townes began working with Arthur Schawlow at Bell Labs where they developed a concept called an “optical maser”, which Townes documented in his lab notebook in September 1957. In 1958, Bell Labs filed a patent application for the optical maser, and Schawlow and Townes submitted a manuscript of their theoretical calculations to the Physical Review, published later that year.
Now this is where the history of the laser starts to get tricky, and scientists theories and concepts began to overlap. In November 1957, Townes met with graduate student Gordon Gould at Columbia University. At the time, Gould was working on his doctoral thesis on the energy levels of excited thallium, and Townes was interested in discussing thallium lamps for optical pumping with him. During their discussion Gould and Townes spoke of radiation emission and afterwards Gould noted his idea for a “laser”, which included using an open resonator, and had his notebook notarized. At about the same time in Russia, Prokhorov independently published the idea of using an open resonator design in his work. In addition, Schawlow and Townes had agreed to an open resonator design for their optical maser – apparently unaware of Prokhorov’s publication and Gould’s unpublished work.
In early 1959, while working for Technical Research Group (TRP), Gould and TRP applied for laser patents related to Gould’s ideas. At a conference that year, Gould published his paper The LASER, Light Amplification by Stimulated Emission of Radiation, the first published use of the term “laser”.
In March 1960, Townes and Schawlow, at Bell Labs, were granted a patent for the optical maser, which today is called a laser. Gould and TRP’s patents applications were denied, which provoked a 28-year patent dispute over the laser invention. (It wasn’t until late 1977- that Gould was issued his first patent related to lasers and 1988 when he began receiving royalties.)
After Townes and Schawlow’s optical maser article was published in 1958, scientists throughout the US became intrigued by their concept, and the race to build a working laser began. Hughes Research Labs, RCA Labs, Lincoln Labs, IBM, Bell Labs, Technical Research Group, Westinghouse, and Siemens all were all competing to build the first functional laser.
At Hughes Research Laboratories, Theodore Maiman discovered that high gain pulsed oscillation could be achieved in synthetic ruby by optically pumping with a solid-state flash lamp; on May 16th 1960, Maiman operated the first functioning laser (capable of pulsed operation*). Maiman promptly submitted a short report on his findings to the Physical Review, but the editors turned it down. Eager to quickly publish his work, Maiman submitted his report to Nature, where it was published in August, 1960. With Maiman’s publication on the way, Hughes Research Laboratory made the first public announcement of the working laser on July 7, 1960 – the race was over.
*It should also be noted, that the first successful continuous output ruby laser was built two years later by Willard Boyle at Bell Labs.
Even with the controversy over who invented the laser, the work of these laser pioneers sparked a technological revolution. Townes, Basov, and Prokhorov shared the 1964 Nobel Prize in Physics for their fundamental work in the field of quantum electronics, which led to the construction of oscillators and amplifiers based on the maser-laser principle. Schawlow shared the 1981 Nobel Prize in Physics with Nicolaas Bloembergen and Kai Siegbahn for their contributions to the development of laser spectroscopy. And, there are already at least ten other Nobel Prize winners whose work was made possible by lasers! At IV Lab, we use lasers for a variety of research processes, most notably our femtosecond spectrometer (check out the blog post).
Today, the laser has become so common that few people realize that laser, now a noun, was originally an acronym for “light amplification by stimulated emission of radiation.” To learn how the ruby laser works, check it out on wikipedia. Or, if you are interested in a more detailed history or timeline of the laser and its patent controversy click the links below.
Photonics Spectra: A History of the Laser: A Trip Through the Light Fantastic
Academic Press: The Race to Make the Laser
Physics Today: Bell Labs and the Ruby Laser
A Century of Nature: The First Laser