LASER is the acronym for Light Amplification by Stimulated Emission of Radiation.
Albert Einstein first explained the theory of stimulated emission in 1917, which became the basis of Laser. He postulated that, when the population inversion exists between upper and lower levels among atomic systems, it is possible to realize amplified stimulated emission and the stimulated emission has the same frequency and phase as the incident radiation. However, it was in late 1940s and fifties that scientists and engineers did extensive work to realize a practical device based on the principle of stimulated emission. Notable scientists who pioneered the work include Charles Townes, Joseph Weber, Alexander Prokhorov and Nikolai G Basov.
Initially, the scientists and engineers were working towards the realization of a MASER (Microwave Amplification by the Stimulated Emission of Radiation), a device that amplified microwaves for its immediate application in microwave communication systems. Townes and the other engineers believed it to be possible create an optical maser, a device for creating powerful beams of light using higher frequency energy to stimulate what was to become termed the lasing medium. Despite the pioneering work of Townes and Prokhorov it was left to Theodore Maiman in 1960 to invent the first Laser using ruby as a lasing medium that was stimulated using high energy flashes of intense light.
The development of Lasers has been a turning point in the history of science and engineering. It has produced a completely new type of systems with potentials for applications in a wide variety of fields. During sixties, lot of work had been carried out on the basic development of almost all the major lasers including high power gas dynamic and chemical lasers. Almost all the practical applications of these lasers in defense as well as in industry were also identified during this period. The motivation of using the high power lasers in strategic scenario was a great driving force for the rapid development of these high power lasers. In early seventies, megawatt class carbon dioxide gas dynamic laser was successfully developed and tested against typical military targets. The development of chemical lasers, free electron and X-ray lasers took slightly longer time because of involvement of multidisciplinary approach.
The major steps of advances or breakthroughs in Laser research are given below:
1917: Einstein, A. - Concept and theory of stimulated light emission
1948: Gabor, D. - Invention of holography
1951: Charles H Townes, Alexander Prokhorov, Nikolai G Basov, Joseph Weber - The invention of the MASER (Microwave Amplification of Stimulated Emission of Radiation) at Columbia University, Lebedev Laboratories, Moscow and University of Maryland.
1956: Bloembergen, N. - Solid-state maser- [Proposal for a new type of solid state maser] at Harvard University.
1958: Schawlow, A.L. and Townes, C.H. - Proposed the realization of masers for light and infrared at Columbia University .
1960: Maiman, T.H. - Realization of first working LASER based on Ruby at Hughes Research Laboratories.
1961: Javan, A., Bennet, W.R. and Herriot, D.R. - First gas laser : Helium- Neon (He-Ne laser) at Bell Laboratories.
1961: Fox, A.G., Li, T. - Theory of optical resonators at Bell Laboratories.
1962: Hall,R. - First Semiconductor laser (Gallium-Arsenide laser) at General Electric Labs.
1962: McClung,F.J and Hellwarth, R.W. - Giant pulse generation / Q-Switching.
1962: Johnson, L.F., Boyd, G.D., Nassau, K and Sodden, R.R. - Continuous wave solid-state laser.
1964: Geusic, J.E., Markos, H.M., Van Uiteit, L.G. - Development of first working Nd:YAG LASER at Bell Labs.
1964: Patel, C.K.N. - Development of CO2 LASER at Bell Labs.
1964: Bridges, W. - Development of Argon Ion LASER a Hughes Labs.
1965: Pimentel, G. and Kasper, J. V. V. - First chemical LASER at University of California, Berkley.
1965: Bloembergen, N. - Wave propagation in nonlinear media.
1966: Silfvast, W., Fowles, G. and Hopkins - First metal vapor LASER - Zn/Cd - at University of Utah.
1966: Walter, W.T., Solomon, N., Piltch, M and Gould, G. - Metal vapor laser.
1966: Sorokin, P. and Lankard, J. - Demonstration of first Dye Laser action at IBM Labs.
1966: AVCO Research Laboratory, USA. - First Gas Dynamic Laser based on CO2
1970: Nikolai Basov's Group - First Excimer LASER at Lebedev Labs, Moscow based on Xenon (Xe) only.
1974: Ewing, J.J. and Brau, C. - First rare gas halide excimer at Avco Everet Labs.
1977: John M J Madey's Group - First free electron laser at Stanford University.
1977: McDermott, W.E., Pehelkin, N.R,. Benard, D.J and Bousek, R.R. - Chemical Oxygen Iodine Laser (COIL).
1980: Geoffrey Pert's Group - First report of X-ray lasing action, Hull University, UK.
1984: Dennis Matthew's Group - First reported demonstration of a "laboratory" X-ray laser from Lawrence Livermore Labs.
1999: Herbelin,J.M., Henshaw, T.L., Rafferty, B.D., Anderson, B.T., Tate, R.F., Madden, T.J., Mankey II, G.C and Hager, G.D. - All Gas-Phase Chemical Iodine Laser (AGIL).
2001: Lawrence Livermore National Laboratory - Solid State Heat Capacity Laser (SSHCL).