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![Maser and Lasers: Looking Back Fifty+ Years
Laser Pre-history 1916—1950
1916—1940 Quantum theory emerges, stimulated emission understood
1940—1950 Optical pumping, magnetic resonance physics are developed
July 1946 First observation of man-made population inversion?
The Maser Era 1950—1960
1951—1956 Ammonia maser, then microwave solid-state maser
1956—1959 Maser concepts evolve towards the laser
The Laser Era Opens 1960—1966
May 1960 Maiman s ruby laser breaks open the laser era
1960—1966 Laser technology evolves with immense rapidity
Lasers, then and now 1966—2002
1966—2000 Lasers in the Tabloids [ Lasers im Bild ]
2002 Laser applications, economics, and continued evolution](https://image.slidesharecdn.com/stanfordlaserhistory-240219102355-30130544/75/Laser-Development-History-Stanford-laser-history-3-2048.jpg)
![1916: Einstein introduces quantum transitions
We introduce the following quantum-theoretical hypothesis. Under the
influence of a radiation density a molecule can make an [upward]
transition from state n to state m by absorbing radiation energy We
similarly assume that a [downward]* transition m to n associated with a
liberation of radiation energy is possible under the influence of the
radiation field, and that it satisfies the [same] probability law
Einstein introduced his A and B coefficients
to distinguish between spontaneous and
stimulated transitions. Van Vleck in 1924
was, however, apparently the first to refer to
downward stimulated transitions as
“stimulated emission”.
E1
E2
N1
N2](https://image.slidesharecdn.com/stanfordlaserhistory-240219102355-30130544/75/Laser-Development-History-Stanford-laser-history-4-2048.jpg)
![1924: Hendrik Kramers adds negative dispersion
If the atom is in one of its higher states, the atom will then give rise
to a kind of anomalous dispersion with the sign of [the induced
polarization] P reversed.
This so called negative dispersion is closely connected with the
prediction made by Einstein, that the atom for such a frequency will
exhibit a negative absorption, I.e. light waves of this frequency, passing
through a great number of atoms in the state under consideration, will
increase in intensity.
excited-state
response
lower-state
response](https://image.slidesharecdn.com/stanfordlaserhistory-240219102355-30130544/75/Laser-Development-History-Stanford-laser-history-6-2048.jpg)
![1947: Lamb & Retherford suggest gas discharges
But for microwave population inversion:
On the basis of the preceding discussion one would expect that
the 2p levels [in a hydrogen discharge] would be about five to ten
times more populated than the 2s levels. In that case, one would
expect to find a negative [microwave-frequency] absorption and as
estimated below a large one . . . . . . . . Phys. Rev., vol. 79 (1950)](https://image.slidesharecdn.com/stanfordlaserhistory-240219102355-30130544/75/Laser-Development-History-Stanford-laser-history-12-2048.jpg)
![1961: First laser medical treatments
“In December 1961 the Columbia-Presbyterian Hospital
used a laser on a human patient for the first time,
destroying a retinal tumor with the American Optical
[ruby laser] photocoagulator.”
Joan Lisa Bromberg
The Laser in America, 1950—1979
Laser History Project / MIT Press, 1991](https://image.slidesharecdn.com/stanfordlaserhistory-240219102355-30130544/75/Laser-Development-History-Stanford-laser-history-32-2048.jpg)
![Lasers im Bild [Lasers in the Tabloids]
¥The real Ruby Laser
¥Mal Stitch s real claim to fame
¥What lasers are really good for
¥Making a really low-cost laser
¥Making a really high-power laser](https://image.slidesharecdn.com/stanfordlaserhistory-240219102355-30130544/75/Laser-Development-History-Stanford-laser-history-38-2048.jpg)
Laser Development History [Stanford laser history]
- 1. May 17, 1960:The first (ruby) laser
- 2. 1950 1940 1960 1930 1915 Ray LymanWilbur J. E. Wallace Sterling Donald Tresidder 1951-54: Charles Townes develops NH3 maser 1956: Nico Bl. invents the microwave s-s maser May 1960: Ted Maiman operates first (ruby) laser 1946: Bloch, Hansen and Packard observe first man-made population inversion Einstein proposes stimulated emission Stanford Industrial Park Honors Coop Pgm Affiliates Pgm Stanford Shopping Ctr Microwave (later Ginzton) Lab founded Felix Bloch Willis Lamb Schawlow W. W. Hansen Ed Ginzton Marvin Chodorow Provost Dean of Engr Prof. of EE tony siegman EE Chair Frederick Emmons Terman: Harvard Radio Research Lab MIT Radiation Laboratory HRRL Director Varian bros invent klystron HP founded WORLD WAR II 1920s & 1930s: Quantum theory and basic maser gain principles understood 1936: WW Hansen invents the microwave cavity 10+ subsequent Nobel Prizes }
- 3. Maser and Lasers:Looking Back Fifty+ Years Laser Pre-history 1916—1950 1916—1940 Quantum theory emerges, stimulated emission understood 1940—1950 Optical pumping, magnetic resonance physics are developed July 1946 First observation of man-made population inversion? The Maser Era 1950—1960 1951—1956 Ammonia maser, then microwave solid-state maser 1956—1959 Maser concepts evolve towards the laser The Laser Era Opens 1960—1966 May 1960 Maiman s ruby laser breaks open the laser era 1960—1966 Laser technology evolves with immense rapidity Lasers, then and now 1966—2002 1966—2000 Lasers in the Tabloids [ Lasers im Bild ] 2002 Laser applications, economics, and continued evolution
- 4. 1916: Einstein introducesquantum transitions We introduce the following quantum-theoretical hypothesis. Under the influence of a radiation density a molecule can make an [upward] transition from state n to state m by absorbing radiation energy We similarly assume that a [downward]* transition m to n associated with a liberation of radiation energy is possible under the influence of the radiation field, and that it satisfies the [same] probability law Einstein introduced his A and B coefficients to distinguish between spontaneous and stimulated transitions. Van Vleck in 1924 was, however, apparently the first to refer to downward stimulated transitions as “stimulated emission”. E1 E2 N1 N2
- 5. 1924: Richard Tolmanhints at amplification The possibility arises that molecules in the upper quantum state may return to the lower quantum state in such a way as to reinforce the primary beam by ‘negative absorption’. The process of negative absorption from analogy with classical mechanics would presumably be of such a nature as to reinforce the primary beam. . . . . . . . . . . . . Phys. Rev., vol. 23 (June 1924) (First recognition of the possibility of maser/laser amplification?)
- 6. 1924: Hendrik Kramersadds negative dispersion If the atom is in one of its higher states, the atom will then give rise to a kind of anomalous dispersion with the sign of [the induced polarization] P reversed. This so called negative dispersion is closely connected with the prediction made by Einstein, that the atom for such a frequency will exhibit a negative absorption, I.e. light waves of this frequency, passing through a great number of atoms in the state under consideration, will increase in intensity. excited-state response lower-state response
- 7. 1933: Ladenburg observesanomalous dispersion ¥ Butnot actual inversion
- 8. Late 1930s— mid 1940s:World War II Massive wartime advances in electronics, radar, rf technology, microwaves, signal processing and communications emerge in the U.S., the U.K. and elsewhere. Many distinguished physicists participate at the Harvard Radio Research Lab, the Radiation Laboratory at MIT ( the Rad Lab Series ), Bell Labs, and elsewhere. End of the war leads to unprecedented government funding of university research in science and engineering; ONR, ARO, AFOSR are created.
- 9. 1940: Fabrikant (USSR)considers device possibilities For molecular (atomic) amplification it is necessary that N2/N1 be greater than g2/g1. Such a situation has not yet been observed in a discharge even though such a ratio of population is in principle attainable Under such conditions we would obtain a radiation output greater than the incident radiation and we could speak of a direct experimental demonstration of the existence of negative absorption. (PhD dissertation, Russian patents, other publications)
- 10. 1946: The firstman-made population inversion? Felix Bloch, W. W. Hansen, Martin Packard: NMR expts in water carried out at Stanford University in July 1946
- 11. A bit moreon W. W. Hansen: Invented the linear accelerator (1947) Before that, invented the microwave cavity (1936)
- 12. 1947: Lamb &Retherford suggest gas discharges But for microwave population inversion: On the basis of the preceding discussion one would expect that the 2p levels [in a hydrogen discharge] would be about five to ten times more populated than the 2s levels. In that case, one would expect to find a negative [microwave-frequency] absorption and as estimated below a large one . . . . . . . . Phys. Rev., vol. 79 (1950)
- 13. 1950: Purcell &Pound s dramatic observations
- 14. The early 1950s:The Maser Era Opens • Townes, Prokhorov and Basov s ammonia maser 1951—1954 • Gordon, Zeiger & Townes, Columbia: proposed 1951, operated 1954 • Prokhorov & Basov, USSR: independent development, similar dates ¥ Nico Bloembergen s microwave solid-state maser 1956–1957 • Proposed at Harvard 1956; operated at Bell Labs 1957 • Really opens the path to the laser ¥ Additional maser proposals 1953—1957 • Joseph Weber’s maser amplification proposal 1953 • Robert Dicke’s maser patent, filed 1956, issued 1958 • Combrisson & Townes 1956; M. W. P. Strandberg 1957
- 15. 1954: Charles Townes,Jim Gordon, & the NH3 maser
- 16. 1956: Bloembergen sMicrowave Solid-State Maser ¥Proposed by Nico Bloembergen at Harvard 1956 • Published in Phys Rev October 1956 • Bloembergen’s basic patent is very far reaching • Successfully operated a few months later at Bell Labs ¥Many immediate extensions & implementations 1958— 1964 • Traveling-wave masers; ruby as a microwave maser material; phonon (acoustic) masers; applications to radio & radar astronomy; Echo satellite experiments; space communications ; planetary radars; Penzias & Wilson’s observation of 3K background radiation…
- 17. 1957: Cavity-type rubymaser X-band (10 Ghz) waveguide pump cavity S-band (3 GHz) rectangular stripline resonance mode Operated at liquid helium temperature, dc magnetic field of a few thousand gauss Very-low-noise microwave amplifier (few MHz bandwidth)
- 18.
- 19. Late 1950s: BellLabs sugar scoop antenna
- 20. Late 1950s: BellLabs Sugar scoop antenna
- 21. Late 1950s: ANobel in the noise
- 22. Late 1950s: Evolvingtoward the laser . . . ¥Gordon Gould & his ideas Nov 1957 • The notebook, the candy store notary, and the Thirty-Year Patent Wars ¥Schawlow & Townes Phys Rev paper 1958 • Detailed analysis of optical maser requirements • Stimulated much interest among other workers ¥Javan, Sanders: gas discharge laser ideas 1959 • Published in PRL ¥The First QE Conference (Shawanga Lodge) Sept 1959 • Brought together all the active people in the field • Proceedings edited by Townes, published by Columbia
- 23. 1959: First QuantumElectronics Conference • Shawanga Lodge (Catskills, NY), September 1959
- 24. 1959: Shawanga MeetingProgram Committee
- 25. 1960: The LaserEra bursts open ¥Ruby laser (6943 A) • Maiman, Asawa & D’Haenens, Hughes Res Labs May 1960 ¥Trivalent uranium in cooled CaF2 (2.5 m) • Sorokin and Stevenson, IBM Res Labs mid–1960 ¥Divalent samarium in CaF2 (7085 A) • Also Sorokin and Stevenson, IBM ~Nov 1960 ¥First He-Ne gas laser (1.15 m) • Javan, Bennett & Herriott, Bell Labs ~Dec 1960 • RF excitation, “collisions of the second kind”
- 26.
- 27. Ted Maiman andhis stubby ruby
- 28. First ruby laser,disassembled
- 29. Arthur Schawlow putsthe laser to use
- 30. 1961— 1962: The laserfield explodes ¥Nd: glass laser Snitzer 1961 ¥Laser Q-switching Hellwarth 1961 ¥Optical harmonic generation Franken 1961 ¥Optical fiber lasers Snitzer 1961 ¥He-Ne 6328A visible laser White & Rigden 1962 ¥Other gas lasers Patel, Bennett, Faust 1962 ¥Raman laser action Woodbury & Ng 1962 ¥GaAs diode lasers GE, IBM, Lincoln Labs 1962
- 31. 1961: Eli Snitzers early fiber lasers
- 32. 1961: First lasermedical treatments “In December 1961 the Columbia-Presbyterian Hospital used a laser on a human patient for the first time, destroying a retinal tumor with the American Optical [ruby laser] photocoagulator.” Joan Lisa Bromberg The Laser in America, 1950—1979 Laser History Project / MIT Press, 1991
- 33. 1963— 1966: The immenselyrapid evolution continues ¥Liquid lasers Lempicki & Samelson 1963 ¥Laser mode locking Various groups 1963 ¥CO2 laser Kumar Patel 1964 ¥Nd:YAG laser Joe Geusic et al 1964 ¥Ion lasers Bill Bridges, Gene Gordon 1964 ¥Iodine photodissociation laser Kasper & Pimentel 1964 ¥HCl chemical laser Kasper & Pimentel 1965 ¥Organic dye lasers Peter Sorokin, Fritz Schaefer 1966
- 34. Charles Townes, Howthe Laser Happened: Adventures of a Scientist (1999)
- 35. Theodore Maiman, The LaserOdyssey (2000)
- 36. LASER: The Inventor,the Nobel Laureate, and the Thirty Year Patent War (biography of Gould by Nick Taylor; 2000)
- 37. 1966— 2002: A fewunusual lasers ¥The real Ruby Laser ¥What are lasers really good for? ¥A really low-cost laser ¥A really high-power laser
- 38. Lasers im Bild[Lasers in the Tabloids] ¥The real Ruby Laser ¥Mal Stitch s real claim to fame ¥What lasers are really good for ¥Making a really low-cost laser ¥Making a really high-power laser
- 39. The real RubyLaser:
- 40. Mal Stitch sreal claim to fame
- 41. (In the earlydays you were still allowed to smoke in your lab ) What are lasers really good for?
- 42. What else arelasers good for? —the laser face-lift
- 43. How to makea really low-cost laser • $300 He-Ne laser, University Laboratories, Berkeley CA, mid–1960s
- 44. Really saving onparts costs . . .
- 45. Israeli gasoline-powered laser (Howmany photons per liter?)
- 46.
- 47. 2002: Laser technologyis still expanding ¥ Current losers ( The dead and the dying ) • Dye lasers, He-Ne lasers, lamp-pumped s-s lasers ¥ Steady state (for now, anyway) • CO2 lasers, ion lasers, excimer lasers ¥ Niche players • He-Cd, Cu vapor; color centers, ruby, alexandrite, FELs ¥ Current winners • Diode lasers of all kinds, DPSSLs, Ti-sapphire, fiber lasers ¥ The near future? • High-power DPSSLs Quantum cascade lasers • High-pwr fiber lasers Fsec lasers
- 48. 0 2 4 6 8 10 12 14 1996 1997 19981999 2000 2001 2002 $B Total laser sales Diode lasers Nondiode lasers 12 B$ 9.5 B$ 2.6 B$ Laser device sales, diode & nondiode, 1997— 2001
- 49. Conventional (I.e., non-diode)laser sales, 2000— 2001 0 200 400 600 800 1000 1200 1400 1600 Medical & therapeutic Basic research Instrumentation Image recording Sensing Other Entertainment Inspection & measurement Optical storage Barcode scanning Mat'ls processing CO2 flowing Diode- pumped solid state CO2 sealed Ion < 1W Other Ion > 1W Laser- pumped solid state Helium- neon Dye He- Cd Lamp- pumped s- s Excimer Year 2001 Year 2000
- 50. Natural masers &lasers ¥ Astrophysical masers (discovered in 1965) • Maser action in interstellar clouds of OH (1670 MHz), H20 (2.2 GHz), SiO2 (4.3–13 GHz) pumped by UV radiation from nearby stars • Brightness temperatures ≥ 1015 K; immense power outputs ¥ CO2 lasers in planetary atmospheres (discovered 1976) • 10 µm amplification in atmospheres of Mars and Venus • Directly pumped by sunlight; low gains ¥ Hydrogen recombination masers (discovered 1994— 1996) • Hydrogen clouds near MWC 349A & other stars • ASE at 850 µm, 450 µm, 169 µm, 89 µm, 52.5 µm
- 51. Special thanks to ¥Myhosts at the MPQ in Garching and elsewhere in Germany for their hospitality ¥Mario Bertolotti, author of Masers and Lasers (Adam Hilger, 1983), for his outstanding book on the intellectual history of masers & lasers ¥Joan Bromberg, The Laser in America, 1950–1979 (Laser History Project / MIT Press, 1991) ¥Mother Nature, who was operating masers and lasers long before we humans discovered them
- 52. Special thanks to ¥TheOptical Sciences Center, for inviting me to speak today ¥Mario Bertolotti, author of Masers and Lasers (Adam Hilger, 1983), for his outstanding book on the intellectual history of masers & lasers ¥Joan Bromberg, The Laser in America, 1950–1979 (Laser History Project / MIT Press, 1991) ¥Mother Nature, who was operating masers and lasers long before we humans discovered them
- 53. Laser history references: ¥MarioBertolotti, Masers and Lasers (Adam Hilger, 1983) —an outstanding book on the intellectual history of masers & lasers ¥Joan Bromberg, The Laser in America, 1950–1979 (MIT Press, 1991) — a bit political, but much detail ¥Mother Nature, who was operating masers and lasers long before we humans discovered them
- 54. Stanford references: ¥ E.Kiester, Jr: Donald B. Tresidder, Stanford's Overlooked Treasure: (Stanford Historical Society 1992) —outstanding ¥ Robert Buderi: The Invention That Changed the World: How a Small Group of Radar Pioneers Won the Second World War and Launched a Technical Revolution (Simon Schuster 1996). ¥ Rebecca Lowen: Creating the Cold War University: The Transformation of Stanford (University of California 1997) —also excessively political, but much fascinating detail ¥ Carolyn Caddes: Portraits of Success: Impressions of Silicon Valley Pioneers (Tioga Publishing 1986) —gives coffee table books a good name
- 55. 1950 1940 1960 1930 1915 Ray LymanWilbur J. E. Wallace Sterling Donald Tresidder 1951-54: Charles Townes develops NH3 maser 1956: Nico Bl. invents the microwave s-s maser May 1960: Ted Maiman operates first (ruby) laser 1946: Bloch, Hansen and Packard observe first man-made population inversion Einstein proposes stimulated emission Stanford Industrial Park Honors Coop Pgm Affiliates Pgm Stanford Shopping Ctr Microwave (later Ginzton) Lab founded Felix Bloch Willis Lamb Schawlow W. W. Hansen Ed Ginzton Marvin Chodorow Provost Dean of Engr Prof. of EE tony siegman EE Chair Frederick Emmons Terman: Harvard Radio Research Lab MIT Radiation Laboratory HRRL Director Varian bros invent klystron HP founded WORLD WAR II 1920s & 1930s: Quantum theory and basic maser gain principles understood 1936: WW Hansen invents the microwave cavity 10+ subsequent Nobel Prizes }