Charles H. Townes invented the microwave-emitting maser in the early 1950s at Columbia University, with the help of Herbert Zeiger and James Gordon. Masers began proliferating in the last half of the 1950s, but even before then a few physicists were looking at prospects for amplifying stimulated emission at wavelengths much shorter than microwaves.
In the Soviet Union, V.A. Fabrikant and his students filed a patent application dated June 18, 1951 on amplifying electromagnetic radiation from the ultraviolet through the radio spectrum, but their idea had little direct effect on laser research, even in the Soviet Union. In the United States, Robert H. Dicke developed the concept of super radiance and what he called the “optical bomb.”
His idea was to use a short excitation pulse to produce an inverted population, which would then generate an intense burst of spontaneous emission. He separately suggested (in 1956) that a pair of parallel mirrors, forming a Fabry-Perot interferometer, could serve as a resonant optical cavity.
The 1958 Paper
The first detailed proposal for building a laser—which at the time they called an “optical maser”—was published by Townes and Arthur L. Schawlow. Schawlow had been a postdoctoral fellow under Townes at Columbia until leaving to join Bell Labs in 1951. … In 1957 both began thinking about the possibility of “infrared and optical masers,” and after discussing the idea over lunch at Bell Labs, decided to collaborate. They spent several months working on the problem, … which led to their famous paper “Infrared and Optical Masers,” published in the December 1958 Physical Review.
That paper had a profound impact on American laser development. Preprints circulated at Bell Labs and Columbia before the journal came out, and formal publication was the starting gun for the great laser race that culminated in completion of the first laser. Not everyone realized its importance, however. Bell Labs attorneys did not think the idea was worth patenting, and filed a patent application only after Townes insisted. That led to U.S. Patent No. 2,929,922, issued in 1960.
Meanwhile, similar ideas were running through the mind of a 37-year old Columbia graduate student, Gordon Gould. At the time, Gould was doing doctoral thesis research under Polykarp Kusch, who shared the 1955 Nobel Prize in Physics with Willis Lamb.
Gould wrote down his laser ideas—including a definition of “laser” as Light Amplification by the Stimulated Emission of Radiation—in late 1957, and had them notarized … in what he hoped was the first step to getting a patent.
The First Inventor?
Credit for “inventing” the laser concept remains controversial. Townes and Schawlow have been widely honored by the scientific community, separately receiving Nobel Prizes in 1964 and 1981. Their Physical Review paper had a profound impact, and was the single biggest event triggering many research efforts that led to early lasers. Gould’s … patent applications [initially] … had only minimal circulation and essentially no impact on most of the scientific world.
Gould made less-important but nonetheless solid contributions in lasers and fiber optics, but by the mid-1970s he had become almost invisible in the laser world. However, he quietly continued pursuing his patent applications, and after a court in 1973 invalidated a patent issued to Townes and Schawlow, he was able to secure a series of patents on laser concepts and applications, starting in 1977. The delay made them far more valuable.
The First Laser, 1960
Among the maser materials considered for use in lasers was synthetic ruby, aluminum oxide doped with chromium atoms. The chromium lines were useful in masers, and their spectroscopy was well known. At Bell Labs, Schawlow considered ruby as a laser material, but in 1959 he publicly dismissed it as unsuitable. That opinion was based on inadequate data, and before long it was proved wrong.
In 1960, researcher Theodore H. Maiman built the first laser, a ruby laser, at Hughes Research Laboratory in California.
Meanwhile, Theodore Maiman was trying to use his knowledge of ruby masers to make a laser at Hughes Research Laboratories in Malibu, CA. He began working with ruby because it was well-known, at first thinking he could switch to a better material later, when he better understood laser requirements. However, he eventually convinced himself that Schawlow was wrong, and that ruby would make a good laser. It could not generate a continuous beam, but he decided pulses were good enough to demonstrate laser action. … He forged ahead, working alone, while Hughes management grew skeptical. By the time he succeeded in making the ruby laser work for the first time, on May 16, 1960, he was not supposed to be working on the program.
Maiman’s laser was small and elegant: a ruby rod, with its ends silvered to reflect light, which he placed inside a spring-shaped flashlamp. His success is undisputed, but he almost immediately ran into problems. The then-new Physical Review Letters summarily rejected his report of making an “optical maser” as “just another maser paper.” The journal’s founding editor Samuel Goudsmit, a theoretician best known as the co-discoverer of electron spin, had grown tired of the glut of maser papers arriving at his office and decided that they no longer merited rapid publication in his journal. Moreover, the journal had just published another paper by Maiman on the spectroscopy of ruby—work that led to his laser demonstration.
Maiman hurriedly prepared a concise 300-word report which was immediately accepted by the British weekly Nature. When efforts to convince Goudsmit of his error failed, the Nature paper, published August 6, 1960, became the first report of a working laser. Maiman later published a more detailed analysis in Physical Review.
Although Maiman had beat everyone else hands down in the great laser race, Townes, [Nikolai] Basov, and Aleksandr Prokhorov received the 1964 Nobel Prize for their work on laser theory.
C. Kumar N. Patel, who pioneered molecular gas lasers, with a flowing-gas laser at Bell Labs in 1967.
Join The Laser Anniversary Celebration
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Laser Lessons Learned
Jeff Hecht’s paper on “Lessons Learned: The Laser from Theory to Practice” for the “Optical Believe It or Not” session at SPIE Optics+Photonics in August 2008 can be found in the SPIE Digital Library.
Jeff Hecht is a science and technology writer who authored "Laser Pioneers" and "Beam: The Race to Make the Laser" along with several tutorials on lasers and fiber optics. This excerpt is reprinted with permission. For more information: jeffhecht.com