section_path: History/Laser
section_name: Laser
paragraph_text: Laser
  
  In April 1957, Japanese engineer Jun-ichi Nishizawa proposed the concept of a " semiconductor optical maser " in a patent application.
  
  That same year, Charles H. Townes and Arthur Leonard Schawlow, then at Bell Labs, began a serious study of infrared "optical masers". As ideas developed, they abandoned infrared radiation to instead concentrate on visible light. In 1958, Bell Labs filed a patent application for their proposed optical maser; and Schawlow and Townes submitted a manuscript of their theoretical calculations to the Physical Review, which was published in 1958.
  
  Simultaneously, Columbia University graduate student Gordon Gould was working on a doctoral thesis about the energy levels of excited thallium. When Gould and Townes met, they spoke of radiation emission, as a general subject; afterward, in November 1957, Gould noted his ideas for a "laser", including using an open resonator (later an essential laser-device component). Moreover, in 1958, Prokhorov independently proposed using an open resonator, the first published appearance of this idea. Meanwhile, Schawlow and Townes had decided on an open-resonator laser design – apparently unaware of Prokhorov's publications and Gould's unpublished laser work.
  
  At a conference in 1959, Gordon Gould first published the acronym "LASER" in the paper The LASER, Light Amplification by Stimulated Emission of Radiation. Gould's intention was that different "-ASER" acronyms should be used for different parts of the spectrum: "XASER" for x-rays, "UVASER" for ultraviolet, etc. "LASER" ended up becoming the generic term for non-microwave devices, although "RASER" was briefly popular for denoting radio-frequency-emitting devices.
  
  Gould's notes included possible applications for a laser, such as spectrometry, interferometry, radar, and nuclear fusion. He continued developing the idea and filed a patent application in April 1959. The United States Patent and Trademark Office (USPTO) denied his application, and awarded a patent to Bell Labs, in 1960. That provoked a twenty-eight-year lawsuit, featuring scientific prestige and money as the stakes. Gould won his first minor patent in 1977, yet it was not until 1987 that he won the first significant patent lawsuit victory when a Federal judge ordered the USPTO to issue patents to Gould for the optically pumped and the gas discharge laser devices. The question of just how to assign credit for inventing the laser remains unresolved by historians.
  
  On May 16, 1960, Theodore H. Maiman operated the first functioning laser at Hughes Research Laboratories, Malibu, California, ahead of several research teams, including those of Townes, at Columbia University, Arthur L. Schawlow, at Bell Labs, and Gould, at the TRG (Technical Research Group) company. Maiman's functional laser used a flashlamp -pumped synthetic ruby crystal to produce red laser light at 694 nanometers wavelength. The device was only capable of pulsed operation, due to its three-level pumping design scheme. Later that year, the Iranian physicist Ali Javan, and William R. Bennett Jr., and Donald R. Herriott, constructed the first gas laser, using helium and neon that was capable of continuous operation in the infrared (U.S. Patent 3,149,290); later, Javan received the Albert Einstein World Award of Science in 1993. In 1962, Robert N. Hall demonstrated the first semiconductor laser, which was made of gallium arsenide and emitted in the near-infrared band of the spectrum at 850 nm. Later that year, Nick Holonyak Jr. demonstrated the first semiconductor laser with a visible emission. This first semiconductor laser could only be used in pulsed-beam operation, and when cooled to liquid nitrogen temperatures (77 K). In 1970, Zhores Alferov, in the USSR, and Izuo Hayashi and Morton Panish of Bell Labs also independently developed room-temperature, continual-operation diode lasers, using the heterojunction structure.