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On the Shoulders of Giants

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For millennia, scholars in the old and new worlds have realized that their efforts depend largely on the works of those who came before. The “eureka!” moments experienced by scientists and other observers of nature do arise, but there must exist first a foundation of knowledge that has been passed down from earlier investigators.

This has never been more true than in the world of laser technology. It would be shocking to find someone in the field who is unaware of names such as Maiman, Townes, Schawlow, and Basov, but the pioneering developments of today depend on the efforts of many more innovators who toiled at the same time, or even earlier.

Entire books have been given over to untangling the web of published papers, patents (submitted, approved or contested), conference presentations, lab tests, and handwritten, notarized paper journals that comprise the forensic evidence of who did what, when. The following is a brief tour of some of the bright lights who, over the past five decades, have brought the laser to prominence. For a comprehensive timeline of the laser’s history, see “A History of the Laser.”

Though no one could have known it at the time, Charles Fabry and Alfred Perot became forever tied to the story of the laser through the creation of the interferometer in the late 19th century. Two perfectly parallel mirrors were the key to stimulating both solid and gaseous molecules to produce an inverted population. Without the Fabry-Perot device, you’re just exciting particles randomly and to no avail.


Charles Fabry (Library of Congress)



A couple of decades later, in 1917, while he was tinkering with other concepts that also caused a stir, Albert Einstein became the first theoretician to stipulate ways in which atoms might interact with photons, including the practicality of producing the stimulated emission of light.


Alfred Perot (Wikimedia Commons)


Scientists in the US, Europe, and the Soviet Union picked at the edges of light-and-matter interactions for several years, with two global wars causing deep distractions. In 1940, the young physicist Valentin A. Fabrikant of the Moscow Power Institute described how population inversion – having more molecules excited than not – would necessarily lead to “molecular amplification,” aka stimulated emission. He applied for a patent (in the USSR) for “a method for the amplification of electromagnetic radiation,” on June 18, 1951. The application was rejected at first, but was eventually approved in 1959 – too late for most of the acclaim he deserved.


Albert Einstein (Wikimedia Commons)


While Fabrikant’s patent churned through the Soviet bureaucracy, Joseph Weber of the University of Maryland made the first public description of coherent microwave radiation in 1952.


Nikolai G. Basov (Wikimedia Commons)


Then, from within the heavy-laboring crowd of microwave specialists, came Charles Hard Townes, who, in 1954, conceived and built the very first operating maser, using ammonia gas as the excitation material. He also coined the term, which is an acronym for “microwave amplification by the stimulated emission of radiation.” Townes, who cut his teeth on microwave technologies while working for Bell Telephone Laboratories from 1933 to 1947, got his maser ideas into operation after moving from Bell to Columbia University in 1948. Herbert Zeiger and James Gordon were his assistants on the maser development project, but he had others, who also went on to carve their niches in the maser and, ultimately, laser fields. Among these were Isaac Abella, Herman Cummins, Ali Javan, and Arthur Schawlow.

Arthur L. Schawlow, who ultimately shared the 1981 Nobel Prize in physics for his breakthroughs in laser-based spectroscopy, worked very closely with Townes during the hectic early years of masers and lasers. Not only did they become close friends, but Schawlow married Townes’ sister, Aurelia.


Alexander M. Prokhorov (Wikimedia Commons)


Among those working feverishly in the nascent maser field at about the same time period as Townes in 1954 were Alexander M. Prokhorov and Nikolai Basov of the Lebedev Physics Institute in Moscow. Together, but independently of Townes, they made pioneering steps toward a working ammonia maser. After Townes, Zeiger, and Gordon produced the first working model, Prokhorov and Basov theorized the first three-level maser system. Although they never built a working device, the concepts they brought forth set up exciting new leaps in several fields, especially spectroscopy. In 1964, Townes, Prokhorov, and Basov were jointly rewarded with the Nobel Prize for their maser efforts. Basov later went on to become the first to apply lasers to the creation and study of thermonuclear plasmas as well as to the initiation of chemical processes.

Nearly two years later, Nicolaas Bloembergen of Harvard University produced the second description of a three-level maser, but this scheme differed in that it used solid matter instead of ammonia gas. Bloembergen, who had already established himself as the builder of the first operating nuclear magnetic resonance (NMR) device, used some of those principles to outline the three-level solid-state maser, but he wasn’t the first to make one. Later, he would share the 1981 physics Nobel with Schawlow and Kai Siegbahn.

Derrick Scovil, working with George Feher and Harold Seidel at Bell Telephone Labs, beat Bloembergen to the first operating three-level maser. The three constructed their device using lanthanum ethyl sulfate doped with gadolinium ions and published their results in 1957.

Also in 1957, several years before the first operating laser was turned on, another of Townes’ assistants, Gordon Gould, coined the term laser, obviously based on maser, with the first letter standing for “light.” Gould’s coinage, along with his technical notes, ultimately helped him gain several important patents for the technology 20 years after the fact. (For more, see “Gordon Gould’s Scientific ‘Patent’ Method,” October 2008 Photonics Spectra.)

Masers, of course, create coherent radiation out of long microwaves. But even as the technology became established, many scoffed that you could get the same results with more compact infrared or – heaven forfend! – visible wavelengths. This didn’t stop others from trying, with various levels of support or funding. Of those making the wild dash toward the modern laser, Theodore H. Maiman of Hughes Research Laboratories was the ultimate “winner of the race.” Maiman built the first laser, using synthetic pink ruby, in May 1960. From there, the field exploded, as did tempers over who created the laser.

Within months, research groups all over were attacking “optical masers.” Ali Javan, whose efforts at Columbia University and Bell Labs led him to work on three-level masers also, turned his interest in population inversions within gases into the development of the first helium-neon laser on Dec. 12, 1960. This was also the first laser to emit coherent light continuously rather than in pulses. Javan was aided by William R. Bennett Jr., who moved on to Yale University and the subsequent development of the first chemical laser, and by Donald R. Herriott.

Since the initial flurry of attempts simply to observe lasing action, the race has continued in many directions – some toward new useful laser media, some toward new applications. Perhaps not too astonishingly, most of the researchers circa 1960 already suspected that coherent light would be a uniquely potent tool for communication, spectroscopy, imaging, surgery, and even displays.

They did not disappoint.

Written by Lynn Savage (2010).


Photonics Spectra
Jun 2019
GLOSSARY
maser
An acronym for microwave amplification by stimulated emission of radiation. Predecessor to the laser, the maser or 'microwave laser' was the first device to produce coherent electromagnetic waves, and was done at microwave frequencies through amplification by stimulated emission. A laser (light amplification by stimulated emission of radiation) is a maser that works over a broader range of higher frequency photons in the ultraviolet and visible portion of the electromagnetic spectrum.
Albert EinsteinAlexander ProkhorovAlfred PerotAli JavanCharles FabryConsumerdiode laserselectromagnetic radiationEuropeFeaturesinterferometersMaimanmasersemiconductor laserslasersHistory of the Laser

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