Not until 1954 did he and fellow researchers at Columbia prove it could be done. Using an electric field to direct excited molecules of ammonia gas into a thumb-sized copper chamber, they managed to get a sustained output of the desired radio waves. The device was given the name maser, for microwave amplification by stimulated emission of radiation, and it proved valuable for spectroscopy, the strengthening of extremely faint radio signals, and a few other purposes. But Townes would soon create a far bigger stir, teaming up with his physicist brother-in-law Arthur Schawlow to show how stimulated emission might be achieved with photons at the much shorter wavelengths of light—hence the name laser, with the "m" giving way to "l." In a landmark paper published in 1958 they explained that light could be reflected back and forth in the energized medium by means of two parallel mirrors, one of them only partly reflective so that the built-up light energy could ultimately escape. Six years later Townes received a Nobel Prize for his work, sharing it with a pair of Soviet scientists, Aleksandr Prochorov and Nikolai Gennadievich Basov, who had independently covered some of the same ground.

The first functioning laser—a synthetic ruby crystal that emitted red light—was built in 1960 by Theodore Maiman, an electrical engineer and physicist at the Hughes Research Laboratories. That epochal event set off a kind of evolutionary explosion. Over the next few decades lasers would take forms as big as a house and as small as a grain of sand. Along with ruby, numerous other solids were put to work as a medium for laser excitation. Various gases proved viable too, as did certain dye-infused liquids and some of the electrically ambivalent materials known as semiconductors. Researchers also developed many ways to excite a laser medium into action, pumping in the necessary energy with flash lamps, other lasers, electricity, and even chemical reactions.

As for the laser light itself, it soon came in a broad range of wavelengths, from infrared to ultraviolet, with the output delivered as either pulses or continuous beams. All laser light has the same highly organized nature, however. In the language of science, it is practically monochromatic (of essentially the same wavelength), coherent (the crests and troughs of the waves perfectly in step, thus combining their energy), and highly directional. The result is an extremely narrow and powerful beam, far less inclined to spread and weaken than a beam of ordinary light, which is composed of a jumble of wavelengths out of step with one another.