The Laser and the History of Stimulated Emission

By Nekud October 14, 2026 26 min read

At 4 p.m. on Monday, 16 May 1960, in a small basement laboratory at Hughes Research Laboratories, a quiet, sandy-haired physicist named Theodore Harold Maiman pressed a button and saw, for the first time in the history of the human species, a pencil-thin beam of pure red light emerge from a small cylindrical device mounted on a heavy steel optical bench. The light came from a synthetic ruby rod, about the size of a fountain pen, that had been excited by a brief, brilliant flash of light from a coiled xenon flash lamp wrapped around the rod. The flash lamp had been charged, in the seconds before the flash, by a bank of capacitors; the ruby rod had been polished to a mirror finish at both ends, with one end fully silvered and the other end partially silvered; and the partial silvering of one end had been the source of the pencil-thin beam that Maiman had just seen. The light was, in technical language, a pulse of coherent red light at 694 nanometres, lasting about three ten-thousandths of a second, and the light was produced by a process that Albert Einstein had first described, in a 1917 paper on the quantum theory of radiation, as ‘stimulated emission’. The device was the first working laser, and the device was, in turn, the foundation of a technology that would, in the next sixty years, change the way we read music, send messages across oceans, perform surgery, build electronics, and measure the distance to the moon. To understand why the laser is one of the most important inventions of the twentieth century, one has to begin with Einstein’s 1917 paper, and one has to follow the story through the laboratories of Columbia University, the Lebedev Institute, Bell Labs, and a small patent attorney’s office in Brooklyn.

Einstein and the 1917 paper on stimulated emission

The laser is, in its theoretical foundations, a child of the quantum theory of radiation. The quantum theory had been developed, in its first form, by Max Planck in 1900, and the theory had been developed, in its second form, by Albert Einstein in 1905. Einstein’s 1905 paper on the photoelectric effect had introduced the idea that light could be understood as a stream of discrete energy packets, or ‘quanta’, and the idea had been the foundation of the quantum theory of light. The quantum theory of light had been developed, in the following decade, by Niels Bohr, who had used the quantum theory of light to develop a model of the atom that explained the discrete spectral lines of hydrogen, and by Einstein himself, who had used the quantum theory of light to develop a theory of the interaction between light and matter. The theory had been developed, in 1916 and 1917, in a series of papers by Einstein on the quantum theory of radiation, and the most important of the papers was the 1917 paper ‘Zur Quantentheorie der Strahlung’ (On the Quantum Theory of Radiation), published in the Physikalische Zeitschrift.

Einstein’s 1917 paper was, on the available evidence, a piece of pure theoretical physics. The paper was concerned with the way in which atoms interact with electromagnetic radiation, and the paper was concerned, in particular, with the statistical mechanics of the interaction. Einstein had, in the paper, distinguished three basic processes by which an atom could interact with a photon. The first process, which Einstein called ‘absorption’, was the process by which an atom absorbs a photon of the right energy and is excited to a higher energy state. The second process, which Einstein called ‘spontaneous emission’, was the process by which an excited atom spontaneously emits a photon and returns to a lower energy state. The third process, which Einstein called ‘stimulated emission’, was the process by which an incident photon stimulates an excited atom to emit a second photon of the same frequency, phase, and direction. The stimulated photon, in turn, could stimulate the emission of further photons, in a chain reaction that would, in principle, produce a large number of photons all of the same frequency, phase, and direction. Einstein had pointed out, in the paper, that the three processes were related by the famous ‘A and B coefficients’ of Einstein, and that the relationship between the coefficients was fixed by the requirement that the radiation be in thermal equilibrium with the matter at a given temperature. The theoretical prediction of stimulated emission was, in the 1917 paper, a curiosity of the statistical mechanics of radiation, and the prediction did not, in 1917, have any obvious practical application.

The practical application of stimulated emission had to wait for the development of the technology of the maser, which was a ‘microwave amplification by stimulated emission of radiation’ that was the direct predecessor of the laser. The maser had been developed, in the early 1950s, by Charles Hard Townes, a physicist at Columbia University, and by two of his students, James P. Gordon and Herbert J. Zeiger. The development of the maser had been, in part, a response to a problem in the field of microwave spectroscopy, where physicists were trying to develop extremely sensitive receivers for the weak microwave signals emitted by molecules in the laboratory and in interstellar space. The maser was, in effect, a device that could amplify a weak microwave signal by stimulated emission, and the device was, in turn, the first practical application of Einstein’s 1917 prediction. The first working maser had been demonstrated by Townes and his students in 1953, and the demonstration had been a major event in the field of microwave physics. The maser had, however, a serious limitation: the device worked only in the microwave region of the electromagnetic spectrum, and the device could not be used to produce coherent radiation in the visible, infrared, or ultraviolet regions. The challenge of extending the principle of the maser to the visible region was, in turn, the challenge that would lead to the laser.

Charles Townes, Gordon Gould, and the optical maser

The challenge of extending the maser principle to the visible region of the spectrum was, in the mid-1950s, a major problem in the field of quantum electronics. The problem had been taken up, independently, by two groups of researchers in the United States and in the Soviet Union. The first group was led by Charles Townes at Columbia University, who had been the inventor of the maser and who was, by the mid-1950s, the most prominent figure in the field. The second group was led by Nikolai Basov and Aleksandr Prokhorov at the Lebedev Institute of Physics in Moscow, who had independently developed a maser of their own. Both groups were, by 1957, working on the problem of extending the maser principle to the visible region, and both groups were, in 1958, on the verge of publishing their ideas. Townes and his brother-in-law Arthur Leonard Schawlow, who was a physicist at Bell Labs, published their ideas in a famous paper in the Physical Review in December 1958. The paper was entitled ‘Infrared and Optical Masers’, and the paper proposed, for the first time in the scientific literature, the use of a Fabry-Perot optical resonator to achieve the stimulated emission of visible light. The paper was, in effect, the theoretical foundation of the laser.

The second group of researchers, who were working on the problem of the optical maser in parallel with Townes and Schawlow, was led by a graduate student at the Polytechnic Institute of Brooklyn named Gordon Gould. Gould had been a graduate student working on a thesis in the field of optical pumping, and Gould had, in November 1957, written down a series of notes in a small laboratory notebook that proposed, in considerable detail, the construction of an optical maser that would use a Fabry-Perot resonator. Gould had, in the notes, coined the acronym ‘LASER’ for ‘Light Amplification by Stimulated Emission of Radiation’, and the acronym had, in due course, displaced the older term ‘optical maser’ in the scientific literature. Gould had taken his notebook to a patent attorney, who had filed a patent application on Gould’s behalf in April 1959. The patent application was, however, contested by the Bell Labs patent department, on the grounds that Gould had derived some of the ideas from his employment at the Polytechnic Institute, and the patent dispute was to last for nearly thirty years. The dispute was, in the end, settled in Gould’s favour, and Gould received a series of patents on the laser that were, in the end, the foundation of a substantial personal fortune. The story of the Gould notebook and the Gould patents is one of the most famous patent disputes in the history of American technology, and the story is, in turn, one of the most important legal episodes in the history of the laser.

The publication of the Townes-Schawlow paper in December 1958 was, in effect, the starting gun for the practical development of the laser. Several laboratories around the world began, in the early months of 1959, to work on the construction of a working laser, and the competition was intense. The principal competing approaches were the use of a gas discharge, the use of a solid-state material such as ruby, and the use of a semiconductor material such as gallium arsenide. The first successful laser was, in the event, the ruby laser, which was developed by Theodore Maiman at Hughes Research Laboratories in Malibu, California, in the early months of 1960. The Hughes Research Laboratories was a small research laboratory that had been established, in 1947, by the Hughes Aircraft Company, and the laboratory was, by the late 1950s, one of the most productive small research laboratories in the United States. Maiman had been hired by Hughes in 1956, after a doctoral thesis at Stanford University on the topic of microwave spectroscopy, and Maiman had been working, in the years after his hire, on the development of a new kind of maser that used a solid-state material rather than a gas. Maiman’s work on the maser had led, in due course, to the idea of using a similar approach to construct an optical maser.

Theodore Maiman and the first ruby laser

Maiman’s first laser was, in the technical sense, a remarkably simple device. The laser consisted of a small cylindrical rod of synthetic ruby, about 5 centimetres long and about 1 centimetre in diameter, that had been polished to a mirror finish at both ends. The ruby rod was wrapped in a helical xenon flash lamp, and the flash lamp was, in turn, connected to a bank of capacitors that could deliver a brief, brilliant flash of light. The flash lamp was, in effect, a powerful photographic flash, and the flash lamp delivered, in about three ten-thousandths of a second, several thousand joules of energy to the ruby rod. The ruby rod, when excited by the flash, emitted a pulse of red light at 694 nanometres, and the light was, in turn, amplified by the partial silvering of one end of the rod, with the result that a pencil-thin beam of coherent red light emerged from the rod. The light was, in effect, a pulse of the kind of coherent red light that Einstein had predicted, in 1917, could be produced by stimulated emission, and the light was, in turn, the first laser light ever produced by the human species.

The first working laser was, in fact, demonstrated on 16 May 1960, in the basement laboratory of the Hughes Research Laboratories, and the demonstration was, on the available evidence, a small, quiet event. Maiman had invited a small group of colleagues to the demonstration, and the demonstration consisted of Maiman pressing the button that triggered the flash lamp and the group observing the pencil-thin red beam on a small white card that Maiman had placed at the end of the ruby rod. The demonstration was, in many respects, the culmination of a long and difficult research effort. Maiman had been working on the ruby laser for nearly a year, and Maiman had, in the course of the work, encountered a series of technical difficulties that had required him to develop a number of novel solutions. The most important of the difficulties had been the problem of the threshold power, which had been the subject of a substantial theoretical debate in the literature. Maiman had, in the course of the work, decided to use a ruby rod that was only lightly doped with chromium, and the decision had been, in the event, the key to the success of the device. The lightly doped ruby had a much lower threshold than the more heavily doped ruby that had been recommended in the theoretical literature, and the lightly doped ruby had, in turn, made the first laser possible.

The publication of the first laser was, in the event, a difficult and controversial process. Maiman had submitted a paper on the first laser to the journal Physical Review Letters, and the paper had been rejected by the editor, Samuel Goudsmit, on the grounds that the paper was ‘not of sufficient interest’ to the readers of the journal. Maiman had, in due course, submitted the paper to the British journal Nature, and the paper had been accepted and published on 6 August 1960. The paper was entitled ‘Stimulated Optical Radiation in Ruby’, and the paper was, in effect, the first published report of the laser in the scientific literature. The publication of the paper in Nature was, in turn, a major event in the field of quantum electronics, and the publication was, in due course, the foundation of the worldwide race to develop practical applications of the laser. The race was, in the event, to last for the rest of the twentieth century and beyond, and the race was, in turn, the foundation of the laser industry of the twenty-first century.

The first laser was followed, in the next few years, by a series of other lasers that extended the principle to new regions of the electromagnetic spectrum. The first gas laser, the helium-neon laser, was demonstrated in 1960 by Ali Javan, William Bennett, and Donald Herriott at Bell Labs. The first semiconductor laser, the gallium arsenide laser, was demonstrated in 1962 by Robert Hall at the General Electric Research Laboratory. The first chemical laser, the hydrogen fluoride laser, was demonstrated in 1965 by George Pimentel and J. V. V. Kasper at the University of California at Berkeley. The first dye laser, which could be tuned to a wide range of frequencies, was demonstrated in 1966 by Peter Sorokin and John Lankard at the IBM Research Laboratory. The first excimer laser, which operates in the ultraviolet, was demonstrated in 1970 by Nikolay Basov and his colleagues at the Lebedev Institute. The first free-electron laser, which can be tuned over a very wide range of frequencies, was demonstrated in 1971 by John Madey at Stanford University. Each of these lasers extended the principle of the original ruby laser to a new region of the electromagnetic spectrum, and each of the lasers opened up a new field of scientific and technological application.

The first applications

The first practical applications of the laser were, in the early 1960s, almost entirely in the field of scientific research. The laser was, in the first instance, a new kind of light source, and the light source was, in turn, a valuable tool for the study of the interaction between light and matter. The first important application of the laser was in the field of Raman spectroscopy, where the intense monochromatic light of the laser was used to excite the Raman scattering of molecules, and the Raman scattering was, in turn, used to study the molecular structure of the molecules. The application of the laser to Raman spectroscopy was, in the early 1960s, the foundation of a new field of molecular spectroscopy, and the new field was, in due course, one of the most important applications of the laser in the field of chemistry. The laser was also used, in the early 1960s, in the field of interferometry, where the coherent light of the laser was used to measure small distances with unprecedented accuracy. The application of the laser to interferometry was, in turn, the foundation of a new field of precision measurement, and the new field was, in due course, the foundation of the laser interferometers that were, in the 1990s and 2000s, used to detect the gravitational waves predicted by Einstein’s general theory of relativity.

The first industrial applications of the laser were, in the early 1960s, in the field of materials processing. The first important industrial application was the use of the laser to drill small holes in hard materials such as diamond and tungsten carbide, and the application was, in turn, the foundation of a new industry of laser materials processing. The first medical applications of the laser were, in the early 1960s, in the field of ophthalmology, where the laser was used to repair detached retinas. The first ophthalmic laser surgery was performed in 1961 by a team at the Columbia-Presbyterian Medical Center, and the application was, in due course, the foundation of a new field of laser surgery. The first military applications of the laser were, in the early 1960s, in the field of rangefinding, where the laser was used to measure the distance to a target with great accuracy. The first military laser rangefinder was, on the available evidence, developed in the early 1960s, and the development was, in due course, the foundation of a substantial military laser industry.

The most important application of the laser, in the long run, was in the field of telecommunications. The application of the laser to telecommunications was, in part, a response to the increasing demand for long-distance communication in the second half of the twentieth century, and the application was, in part, a response to the limitations of the existing copper-wire and microwave systems. The first important telecommunications application of the laser was the use of the laser to transmit telephone signals through the open atmosphere, and the application was, in the late 1960s, the foundation of a new field of free-space optical communication. The free-space optical communication was, however, limited by the weather, and the application was, in due course, displaced by the use of the laser to transmit telephone signals through optical fibres. The first important fibre-optic telecommunications system was, on the available evidence, demonstrated in 1970 by a team at the Corning Glass Works, and the system used a fibre that was, in the early form, very lossy, with about 20 decibels of loss per kilometre. The loss was, in the years after the demonstration, reduced by a series of technical improvements, and the reduction of the loss was, in turn, the foundation of a new industry of fibre-optic telecommunications. The fibre-optic telecommunications industry was, by the end of the twentieth century, the foundation of the global telecommunications network, and the global telecommunications network was, in turn, the foundation of the Internet. The laser was, in effect, the foundation of the modern Internet, and the foundation was, in turn, one of the most important applications of the laser in the history of technology.

The optical disc and the digital revolution

The second most important application of the laser, in the long run, was in the field of optical data storage. The application of the laser to optical data storage was, in part, a response to the increasing demand for storage capacity in the second half of the twentieth century, and the application was, in part, a response to the limitations of the existing magnetic storage media such as the magnetic tape and the magnetic disk. The first important optical data storage system was, on the available evidence, the LaserDisc, which was developed in the late 1970s by a consortium of electronics companies including MCA, Philips, and Pioneer. The LaserDisc used a red helium-neon laser to read the data that had been encoded as a series of pits in a metal-coated plastic disc, and the LaserDisc was, in effect, the first practical optical data storage system. The LaserDisc was, however, a commercial failure, and the failure was, in turn, the foundation of a series of improvements that would lead, in the 1980s, to the compact disc, or CD.

The compact disc was developed in the early 1980s by a consortium of electronics companies including Sony and Philips, and the CD was, in effect, the first commercially successful optical data storage system. The CD used a near-infrared semiconductor laser to read the data that had been encoded as a series of pits in a metal-coated plastic disc, and the CD was, in turn, the foundation of a new industry of digital audio. The digital audio industry was, in turn, the foundation of the digital music industry, and the digital music industry was, in turn, the foundation of the modern music industry. The CD was followed, in the 1990s, by the digital versatile disc, or DVD, which used a red semiconductor laser to read the data, and the DVD was, in turn, the foundation of a new industry of digital video. The DVD was followed, in the 2000s, by the Blu-ray disc, which used a blue semiconductor laser to read the data, and the Blu-ray disc was, in turn, the foundation of a new industry of high-definition digital video. The optical disc industry was, in effect, the foundation of the modern digital entertainment industry, and the digital entertainment industry was, in turn, one of the most important industries of the twenty-first century.

The third most important application of the laser, in the long run, was in the field of optical fibre communication. The application of the laser to optical fibre communication was, in part, a response to the increasing demand for bandwidth in the second half of the twentieth century, and the application was, in part, a response to the limitations of the existing copper-wire and microwave systems. The first important optical fibre communication system was, on the available evidence, demonstrated in 1970 by a team at the Corning Glass Works, and the system used a fibre that was, in the early form, very lossy, with about 20 decibels of loss per kilometre. The loss was, in the years after the demonstration, reduced by a series of technical improvements, and the reduction of the loss was, in turn, the foundation of a new industry of optical fibre communication. The optical fibre communication industry was, by the end of the twentieth century, the foundation of the global telecommunications network, and the global telecommunications network was, in turn, the foundation of the modern Internet. The laser was, in effect, the foundation of the modern Internet, and the foundation was, in turn, one of the most important applications of the laser in the history of technology.

The laser in science and medicine today

The laser is, in the early twenty-first century, one of the most important tools in the fields of science and medicine. The laser is, in the field of science, used in a wide range of applications, from the laser cooling of atoms to the laser interferometric detection of gravitational waves. The laser cooling of atoms was developed, in the 1980s, by Steven Chu, Claude Cohen-Tannoudji, and William D. Phillips, and the technique was, in turn, the foundation of the new field of ultracold atomic physics. The ultracold atomic physics was, in turn, the foundation of the new field of quantum simulation, where arrays of ultracold atoms are used to simulate the behaviour of complex quantum systems. The laser interferometric detection of gravitational waves was, in turn, the foundation of the LIGO observatory, which detected the first gravitational waves in September 2015. The detection of the gravitational waves was, in turn, one of the most important scientific events of the early twenty-first century, and the detection was, in turn, the foundation of a new field of gravitational-wave astronomy.

The laser is, in the field of medicine, used in a wide range of applications, from the laser surgery of the eye to the laser treatment of skin conditions. The laser surgery of the eye, which was, on the available evidence, one of the first medical applications of the laser in the early 1960s, has become, in the early twenty-first century, one of the most important medical applications of the laser. The laser is, in the field of eye surgery, used to perform a wide range of procedures, including the correction of refractive errors by LASIK, the treatment of cataracts by laser phacoemulsification, and the treatment of retinal diseases by photocoagulation. The laser is, in the field of dermatology, used to perform a wide range of procedures, including the removal of tattoos, the treatment of port-wine stains, and the resurfacing of the skin. The laser is, in the field of oncology, used to perform a wide range of procedures, including the photodynamic therapy of cancer and the laser ablation of tumours. The medical applications of the laser were, on the available evidence, one of the most important developments in the history of medicine, and the medical applications were, in turn, the foundation of a new industry of medical laser technology.

The laser is, in the field of manufacturing, used in a wide range of applications, from the laser cutting of steel to the laser welding of plastics. The laser cutting of steel was, on the available evidence, one of the first industrial applications of the laser in the early 1960s, and the application has, in the early twenty-first century, become one of the most important industrial applications of the laser. The laser is, in the field of manufacturing, used to perform a wide range of procedures, including the cutting of metals, the welding of plastics, the marking of products, and the 3D printing of metal parts. The industrial applications of the laser were, on the available evidence, one of the most important developments in the history of manufacturing, and the industrial applications were, in turn, the foundation of a new industry of industrial laser technology. The laser is, in sum, one of the most important inventions of the twentieth century, and the invention is, in turn, the foundation of a substantial fraction of the technological infrastructure of the early twenty-first century.

The legacy of the laser

The legacy of the laser is, in the long history of technology, one of the most remarkable stories of the twentieth century. The legacy began, in 1917, with a theoretical prediction by Albert Einstein that stimulated emission could, in principle, be used to produce coherent light. The prediction was, in 1953, the foundation of the maser, and the maser was, in 1960, the foundation of the laser. The laser was, in turn, the foundation of a series of technologies that have, in the sixty years since 1960, transformed the world. The transformation has been, in the field of telecommunications, the foundation of the global Internet. The transformation has been, in the field of data storage, the foundation of the digital entertainment industry. The transformation has been, in the field of medicine, the foundation of a new field of medical laser technology. The transformation has been, in the field of manufacturing, the foundation of a new field of industrial laser technology. The transformation has been, in the field of science, the foundation of a new field of laser-based science.

The legacy of the laser is, in particular, a legacy of the way in which a small, quiet, theoretical prediction by a single physicist in 1917 could, in the course of about fifty years, be transformed into a technology that would change the world. The transformation was, in part, the work of the physicists who developed the maser and the laser, and the transformation was, in part, the work of the engineers who developed the practical applications of the laser. The transformation was, in part, the work of the entrepreneurs who developed the industries that produced the laser-based products, and the transformation was, in part, the work of the consumers who adopted the laser-based products. The transformation was, in sum, a collaborative effort that involved a substantial fraction of the technological and scientific community of the twentieth century, and the transformation was, in turn, one of the most important features of the technological and scientific history of the twentieth century.

The legacy of the laser is, in the long history of technology, also a legacy of the way in which the basic science of quantum mechanics has been translated into a practical technology. The basic science of quantum mechanics was, in the first decades of the twentieth century, the subject of a great deal of theoretical work, and the work was, in large part, the work of European physicists who were working in the universities of Berlin, Göttingen, Copenhagen, and Cambridge. The basic science of quantum mechanics was, in the 1920s and 1930s, the subject of a great deal of experimental work, and the work was, in large part, the work of European physicists who were working in the laboratories of the great European universities. The basic science of quantum mechanics was, in the 1940s and 1950s, the subject of a great deal of applied work, and the work was, in large part, the work of American physicists who were working in the laboratories of American universities and American industrial research laboratories. The basic science of quantum mechanics was, in the 1960s and 1970s, the subject of a great deal of technological work, and the work was, in large part, the work of American engineers who were working in the laboratories of American industrial research laboratories. The basic science of quantum mechanics was, in the 1980s and 1990s, the subject of a great deal of commercial work, and the work was, in large part, the work of American and Japanese and European companies that were working in the factories of the global electronics industry. The basic science of quantum mechanics was, in the 2000s and 2010s, the subject of a great deal of consumer work, and the work was, in large part, the work of the global consumer electronics industry. The basic science of quantum mechanics was, in sum, translated from a European theoretical physics to a global consumer product in the course of about a hundred years, and the translation was, in turn, one of the most important features of the technological and scientific history of the twentieth century.

The laser is, in sum, one of the most important inventions of the twentieth century, and the invention is, in turn, the foundation of a substantial fraction of the technological infrastructure of the early twenty-first century. The invention was, in part, the work of a small group of theoretical physicists who had, in the early twentieth century, developed the basic science of quantum mechanics. The invention was, in part, the work of a small group of experimental physicists who had, in the 1950s, developed the basic technology of the maser. The invention was, in part, the work of a small group of engineers who had, in the 1960s, developed the basic technology of the laser. The invention was, in part, the work of a large group of industrial scientists who had, in the 1970s and 1980s, developed the practical applications of the laser. The invention was, in part, the work of a large group of consumers who had, in the 1990s and 2000s, adopted the practical applications of the laser. The invention was, in sum, a collaborative effort that involved a substantial fraction of the technological and scientific community of the twentieth century, and the invention was, in turn, one of the most important features of the technological and scientific history of the twentieth century.