Jeff Hecht, Laser Focus World Author BEAM: the Race to Make the Laser jeff@jeffhecht.com http://www.jeffhecht.com

Photo courtesy of Kathleen Maiman

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50 years since May 16, 1960

  Background   Ted Maiman and the first laser   Impact of the first laser   Other lasers

  He-Ne, Neodymium, CO2, Diode, etc.   Developing laser applications   Looking to the future

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The Starting Point -- Microwave Maser Charles Townes and James Gordon (1954)

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  3-level solid-state masers - 1956   Nicolaas Bloembergen, Harvard   Derrick Scovil

  Ruby maser - Chihiro Kikuchi, 1957   4°K liquid helium cooling; 2.5 tons, desk-sized

  Military Funding   Sought more practical, compact design   Army contract to Hughes Research Labs

  Ted Maiman redesigned with internal magnet, liquid N2   Reduced to a few pounds

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  Optical is next higher accessible frequency band   Terahertz, far-IR undeveloped

  Proposals   Valentin Fabrikant, Russia, 1939, optical amplifier   1950s US: Robert Dicke, John von Neumann

  Charles Townes starts first serious effort 1957   Examined analytically and posed physics problem

  What would be needed for "optical maser"   Talks with Gordon Gould about optical pumping

  Gould goes off and designs laser   Townes and Schawlow solve same problem

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  Fabry Perot resonator (Gould)

  Schawlow-Townes use same approach   Both require a suitable material

  Population inversion, stimulated emission

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  Optically pumped metal vapor   Alkali metals

  Potassium, cesium, etc   Lamps pump narrow

lines   Very selective excitation   Low power

  Fairly simple physics   Difficult to work with   Gould, Townes

  Electrically excited gas   Noble gases

  Helium, neon, argon   Others possible

  RF or DC discharge   Somewhat simple physics

  Spectra well known   Relatively efficient   Easier to work with   Javan, Bennett at Bell

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  Optically pumped dielectric solids   Precedent in solid-state microwave masers

  Ruby   Rare earths

  Physically complex systems   Potentially simple to use   Optical materials not well developed

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  First QEC Sep 14-16, 1959   Most papers on microwave masers

  Slow progress on He-Ne lasers at Bell Labs   Slow progress on metal vapors at Columbia   Schawlow says ruby won't work

  3-level laser, low fluorescence efficiency   ARPA-TRG program just getting started

  Million dollar grant, parallel effort, mostly classified   Doubts about laser

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  BS EE, U of Colorado   PhD, Physics, Stanford, with Willis Lamb   Working at Hughes Research Laboratories

  Finished ruby microwave maser   Seeking new project

  Optically pumping microwave maser   Would reduce noise

  Noise increased with temperature   Became an issue with liquid nitrogen operation

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  Tougher challenge than microwave maser   Potentially high rewards   Sought "simple, compact and rugged" material

  Could ruby work?   Maiman knew it from microwave maser   Maiman wasn't convinced by Schawlow's analysis   Where was energy going?

  Measured fluorescence for himself   It was near 100%

  Went for optically pumped laser

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  Continuous lamps   Carbon arc – fumes, excess heat   AH6 arc lamp (high-power projector)

  Would barely provide enough energy   ‘It was very hard to get excited about a marginal design’

  Pulsed sources   Exploding wires too messy, poor source   Xenon photographic flashlamp (Leo Levitt)

  Color temperature 7700° C – ruby needed 4700°C   3 coiled models readily available

  Enough to demonstrate laser emission

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  Maiman's group moves from Culver City to Malibu

  Maiman works at home   Writes paper on measurements   Shows management he's doing something   Avoids telling them much

  Designs ruby laser   Managers still in Culver City

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  Stepped up flashlamp power   Turned up voltage   Measured spectrum   Measured pulse

duration and decay   Oscilloscope trace

  Threshold about 950 V   Worked first time   Beam quality modest

  New crystals improved

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Ruby Laser Impact

  Proved laser was feasible   First solid-state laser   New approach to laser operation

  Pulsed operation   High gain

  Well engineered and easy to replicate   Small and simple   Used readily available components   TRG, Bell, others replicated within weeks

  Made lasers accessible   Ruby became first commercial laser

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  Publication problems led to press conference   Muddied historical record   Replication was acid test of success

  Observations and lessons   Start with materials you know.   Brilliant inventions look obvious in hindsight.   Physically ‘simple’ systems can be very complex in

practice   Good engineering complements good science

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The Mixed Rewards of Fame

Courtesy of Kathleen Maiman

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Laser Boom followed

  Helium-neon laser   Neodymium lasers   Semiconductor diode lasers   Carbon dioxide lasers   Ion lasers   Rare-gas halide excimer lasers   Many more

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Launching other laser development

  Sorokin and Stevenson

  IBM Watson   Ur:CaF2   Sm:CaF2

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Red ruby lasers (Dec 1960)

Art Schawlow, Bell Irwin Wieder Varian

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Javan, Bennett, Herriott, Dec 1960 1.15-µm helium-neon laser, Bell Labs

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Dane Rigden, Alan White, 632.8-nm Helium-Neon Laser, Bell, 1962

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Alan White, Dane Rigden, 632.8-nm Helium-Neon Laser, Bell, 1962

What the lab really looked like

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Neodymium lasers

  Nd:Ca-tungstate, pulsed then CW   L. F. Johnson and Kurt Nassau, Bell 1961

  Nd:glass 1961   Elias Snitzer, American Optical

  Nd:YAG, 1964   Joseph E. Geusic, L. G. Van Uitert, Bell

Snitzer 1964 made coiled fiber amplifier to place on linear lamp

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Semiconductor diode lasers

  Robert Hall et al, GE R&D Labs 1962   Homostructure GaAs diode laser   Pulsed and cryogenically cooled

Fenner, Hall and Kingsley

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Kumar Patel, CO2 laser, Bell Labs, 1964

1967 photo, higher power CO2

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Bill Bridges, Ar-Ion Laser, Hughes 1964 Developed CW with Gene Gordon, Ed Labuda, Bell Labs

1969 photo

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Rare-gas halide "excimer" lasers-mid 1970s

  Stuart Searles, Gary Hart, Nick Djeu NRL   J. J. Ewing and Charles Brau, Avco Everett   Earl Ault, Mani Bhaumik, Northrop   Gary Tisone and A.K. Hays, Sandia

Tisone and Hays ArF e-beam pump

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John Madey, 1970s, free-electron lasers – Stanford

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  First wave of small companies   TRG, defense research   Trion Instruments, ruby lasers

  Ann Arbor, spinoff of U of Michigan   Korad, ruby lasers

  Maiman, spinoff of Hughes   Spectra-Physics, helium-neon

  Silicon valley, spinoff of Varian   Optics Technology, ruby, He-Ne

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  Hughes Aircraft – copies of Maiman's   Raytheon – industrial lasers   American Optical - glass lasers   RCA – gas, diodes   Perkin-Elmer (He-Ne with Spectra)   Martin-Marietta   General Electric (mostly research)   IBM (mostly research)   Westinghouse (mostly research)

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  July 7, 1960 Hughes press conference   Increasing number of available

communications channels – fiber optics   True amplification of light – fiber amplifiers   Probing matter for basic research - many   Concentrating light for industry, chemistry and

medicine – many examples   High-power beams for space communications

– not there yet

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  "A solution looking for a problem."   Irnee D'Haenens, assistant to Ted Maiman

  Pulsed ruby lasers   Non-contact materials working, hole drilling   Dermatology, ophthalmology (detached retina)

  CW helium-neon lasers   Measurement and alignment   Communications, information processing

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3D Holography

Emmett Leith and Juris Upatnieks 1964 Courtesy Juris Upatnieks

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  Diode lasers   Ranging   Directly modulated communications

  CO2 lasers   CW cutting   Laser surgery

  Ion lasers   Visible displays, UV sources, info-tech

  Neodymium lasers   Metal working, CW or higher rep rate

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Laser Light Shows and Displays

Laserium Courtesy of Ivan Dryer

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  Government: $150 million   Military equipment (rangefinder/designators)   'Energy' research (laser fusion, isotopes)   Other (R&D, equipment)

  Civilian: $120 million   Industrial   Measurement   Medicine   Information handling

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Emerging applications 1975

Inside a supermarket scanner Auto underbody welding @ Ford

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From fusion to fiber

LLNL Argus Laser 1976 Early fiber system 1979

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  Laser videodisk   MCA, Philips, Thomson-CSF   12-inch disk, one hour per side   He-Ne player (cheap mass-produced tubes)   Led to CDs, other optical disks

  Supermarket scanners   UPC recently adopted

  Printed bar codes   He-Ne reader in checkout counter   Slowed by safety concerns, economy   Took off circa 1980

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  Initially driven by fiber communications   Bell Labs million-hour GaAs laser 1977   Shift to InGaAsP for longer links, higher speed

  Mass production for CD players   Started as $1000 toy for audiophiles   Quickly gained market leverage   Used GaAs lasers developed for telecom   Spinoffs in computer data storage, CD-ROM

  Diode laser printers for PCs   Scaled down from high-speed mainframe laser printers

based on gas lasers

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43 Hecht - Maiman and 50 years of lasers SDI chemical laser battle station

DoD art

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  MCI network early 1980s, long-haul   Submarine cables, TAT-8 - 1988

  Revolution in global phone network   Early 1990s developments

  Erbium-doped fiber amplifiers   WDM becomes practical – huge capacity

  Internet and World Wide Web   Bubble madness

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  Laser refractive surgery   ArF lasers, LASIK, etc.

  Excimer lasers become photolithography source for semiconductor fab   KrF 248 nm   ArF 193 nm

  Laser skin resurfacing and hair removal   Various lasers

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  Second diode laser revolution   Red diodes   High-power pump lasers   Blue diode lasers   Telecommunications lasers

  Diode-pumped solid-state laser revolution   Fiber lasers, rods, slabs

  Ultrafast laser revolution   Femtosecond pulses,   Titanium-sapphire   Frequency combs

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Alfred Leitenstorfer U. Konstanz Nature Photonics

(doi: 10.1038/NPHOTON.2009.258)

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  High efficiency, high-power solid state lasers   Thin disk lasers   Fiber lasers   Direct diodes   Seriously high powers – 100 kW class

  Wavelengths on demand   Nonlinear optics, tunability, new materials   OPSLs/VECSELs (thin-disk semiconductors)

  Ultrashort pulse lasers   Femtosecond frequency combs   High intensity pulses

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  Metamaterials   Nanophotonics   Plasmonics   Photonic crystals   Microstructured optical fibers   Open new possibilities

  New classes of optical properties   Better confinement of light   Stronger interactions

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New facilities: National Ignition Facility

1.8 MJ @355 nm

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Linac Coherent Light Source Free-electron laser 0.15-1.5 nm

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  Higher speed telecommunications   Expanded backbone, 100-Gbit/s line rate   IP-TV fiber to the home

  Expansion of medical diagnostics   Individually tailored medicine

  Consumer products   Laser nano-projectors   Higher-efficiency fluorescent lighting   Think convenient, efficient and fun

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  Advances in direct diode technology   Beam combination   Wavelength shifting

  Synergies with new photonics technology   Metamaterials, photonic crystals   Nanophotonics, plasmonics

  Social/economic/commercial priorities   Energy efficiency, production, conservation   China, India, Developing countries

  The Unexpected

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Physics Today Oct 2007