Lasers in historical perspective

During the past century, advances in physics have interacted with the needs of technology to permit new devices and opportunities in electronics. A persistent theme through most of this time has been the growth of methods of generating and controlling electromagnetic waves, and the extension of these techniques to shorter wavelengths. The discoveries in quantum physics led up to the use of atoms and molecules as resonators, and eventually as active devices such as lasers, for wavelengths too short for electron tubes. More recently accelerator technology, developed for nuclear physics, has made possible free-electron lasers in the optical wavelength regions.