Who Invented The Laser?
Laser (LA-SER) is an acronym composed of the initials of English Light Amplification by Stimulated Emission of Radiation, which means amplified by the light emitted by the laser.
The word laser in English is derived from the initial acronym LASER, which means abbreviation of the English word "excited radiation amplifier".
The key concepts in laser technology were already established when Einstein proposed "stimulated radiation" in 1917. The word laser was once controversial; Gordon Gould was the first person to use this term in the record.
In 1953, the American physicist Charles Hud Towns and his student Arthur Sholow made the first microwave quantum amplifier, which obtained highly coherent microbeams.
In 1958, C.H. Towns and A.L. Show Low extended the principle of microwave quantum amplifier to the optical frequency range.
In 1960, T.H. Theodore Mayman made the first ruby laser.
In 1961, Iranian scientist A. Jia Wen and others made a helium-neon laser.
In 1962, R.N. Hall and others created a gallium arsenide semiconductor laser.
In 2013, researchers at the National Laser Center of the South African Scientific and Industrial Research Council developed the world ’s first digital laser, opening up new prospects for laser applications. The research results were published in the British "Nature Communication" magazine on August 2, 2013.
Types and uses of lasers
The quality of the light emitted by the laser is pure and the spectrum is stable, which can be applied in many ways.
Ruby laser: The original laser was ruby excited by a bright flash bulb, and the laser produced was a "pulse laser" instead of a continuous and stable beam. The quality of the beam produced by this type of laser is essentially different from the laser produced by the laser diode we are using. This intense light emission lasting only a few nanoseconds is very suitable for capturing easily moving objects, such as shooting holographic portraits. The first laser portrait was born in 1967. Ruby lasers require expensive rubies and can only produce short pulsed light.
HeNe laser: In 1960, scientists Ali Javan, William R. Brennet Jr. and Donald Herriot designed the HeNe laser. This is the first gas laser. This laser is commonly used by holographic photographers. Two advantages: 1. Produce continuous laser output; 2. Do not need flash bulbs for light excitation, and use electricity to stimulate gas.
Laser diode: Laser diode is one of the most commonly used lasers. The phenomenon of spontaneous recombination of electrons and holes on both sides of the diode's PN junction is called spontaneous radiation. When the photons generated by spontaneous radiation pass through the semiconductor, once they pass the vicinity of the emitted electron-hole pair, they can be excited to recombine and generate new photons. This photon induces the excited carriers to recombine and emit new photons. This phenomenon is called stimulated radiation. If the injection current is large enough, a carrier distribution opposite to the thermal equilibrium state will be formed, that is, the number of particles will be reversed. When the carriers in the active layer are reversed in a large amount, a small amount of photons generated by spontaneous radiation will generate inductive radiation due to the reciprocal reflection at both ends of the resonant cavity, resulting in positive feedback of frequency selective resonance, or a gain at a certain frequency. When the gain is greater than the absorption loss, coherent light with a good spectral line-laser can be emitted from the PN junction. The invention of laser diodes has enabled the rapid spread of laser applications. Various types of information scanning, fiber optic communications, laser ranging, laser radar, laser records, laser pointers, supermarket collections, etc., are being continuously developed and popularized.