Jeff Hecht, Laser Focus World Author BEAM: the Race to Make the Laser [email protected] http://www.jeffhecht.com

Photo courtesy of Kathleen Maiman 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

Hecht - Maiman and 50 years of lasers 2 The Starting Point -- Microwave Maser Charles Townes and James Gordon (1954)

Hecht - Maiman and 50 years of lasers 3  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

Hecht - Maiman and 50 years of lasers 4  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 Hecht - Maiman and 50 years of lasers 5  Fabry Perot resonator (Gould)

 Schawlow-Townes use same approach  Both require a suitable material  Population inversion, stimulated emission

Hecht - Maiman and 50 years of lasers 6  Optically pumped  Electrically excited gas metal vapor  Noble gases  Helium, neon, argon  Alkali metals  Others possible  Potassium, cesium, etc   Lamps pump narrow RF or DC discharge lines  Somewhat simple physics  Very selective excitation  Spectra well known  Low power  Relatively efficient  Fairly simple physics  Easier to work with  Difficult to work with  Javan, Bennett at Bell  Gould, Townes

Hecht - Maiman and 50 years of lasers 7  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

Hecht - Maiman and 50 years of lasers 8  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

Hecht - Maiman and 50 years of lasers 9  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

Hecht - Maiman and 50 years of lasers 10  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

Hecht - Maiman and 50 years of lasers 11  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

Hecht - Maiman and 50 years of lasers 12  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

Hecht - Maiman and 50 years of lasers 13 Hecht - Maiman and 50 years of lasers 14  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

Hecht - Maiman and 50 years of lasers 15 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

Hecht - Maiman and 50 years of lasers 16  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

Hecht - Maiman and 50 years of lasers 17 The Mixed Rewards of Fame

Courtesy of Kathleen Maiman Hecht - Maiman and 50 years of lasers 18 Laser Boom followed

 Helium-neon laser

 Neodymium lasers

 Semiconductor diode lasers

 Carbon dioxide lasers

 Ion lasers

 Rare-gas halide excimer lasers

 Many more

Hecht - Maiman and 50 years of lasers 19 Launching other laser development

 Sorokin and Stevenson

 IBM Watson

 Ur:CaF2

 Sm:CaF2

Hecht - Maiman and 50 years of lasers 20 Red ruby lasers (Dec 1960)

Art Schawlow, Bell Irwin Wieder Varian

Hecht - Maiman and 50 years of lasers 21 Javan, Bennett, Herriott, Dec 1960 1.15-µm helium-neon laser, Bell Labs

Hecht - Maiman and 50 years of lasers 22 Dane Rigden, Alan White, 632.8-nm Helium- Neon Laser, Bell, 1962

Hecht - Maiman and 50 years of lasers 23 Alan White, Dane Rigden, 632.8-nm Helium- Neon Laser, Bell, 1962

What the lab really looked like Hecht - Maiman and 50 years of lasers 24 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

Hecht - Maiman and 50 years of lasers 25 Semiconductor diode lasers

 Robert Hall et al, GE R&D Labs 1962

 Homostructure GaAs diode laser

 Pulsed and cryogenically cooled

Fenner, Hall and Kingsley

Hecht - Maiman and 50 years of lasers 26 Kumar Patel, CO2 laser, Bell Labs, 1964

1967 photo, higher power CO2 Hecht - Maiman and 50 years of lasers 27 Bill Bridges, Ar-Ion Laser, Hughes 1964 Developed CW with Gene Gordon, Ed Labuda, Bell Labs

1969 photo Hecht - Maiman and 50 years of lasers 28 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

Hecht - Maiman and 50 years of lasers 29 John Madey, 1970s, free-electron lasers – Stanford

Hecht - Maiman and 50 years of lasers 30  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

Hecht - Maiman and 50 years of lasers 31  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)

Hecht - Maiman and 50 years of lasers 32  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

Hecht - Maiman and 50 years of lasers 33  "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

Hecht - Maiman and 50 years of lasers 34 3D Holography

Emmett Leith and Juris Upatnieks 1964 Courtesy Juris Upatnieks Hecht - Maiman and 50 years of lasers 35  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

Hecht - Maiman and 50 years of lasers 36 Laser Light Shows and Displays

Laserium Courtesy of Ivan Dryer

Hecht - Maiman and 50 years of lasers 37  Government: $150 million

 Military equipment (rangefinder/designators)

 'Energy' research (laser fusion, isotopes)

 Other (R&D, equipment)

 Civilian: $120 million

 Industrial

 Measurement

 Medicine

 Information handling

Hecht - Maiman and 50 years of lasers 38 Emerging applications 1975

Inside a supermarket scanner Auto underbody welding @ Ford Hecht - Maiman and 50 years of lasers 39 From fusion to fiber

LLNL Argus Laser 1976 Early fiber system 1979 Hecht - Maiman and 50 years of lasers 40  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

Hecht - Maiman and 50 years of lasers 41  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

Hecht - Maiman and 50 years of lasers 42 SDI chemical laser battle station Hecht - Maiman and 50 years of lasers DoD art 43  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

Hecht - Maiman and 50 years of lasers 44  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

Hecht - Maiman and 50 years of lasers 45  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

Hecht - Maiman and 50 years of lasers 46 Alfred Leitenstorfer U. Konstanz Nature Photonics

(doi: 10.1038/NPHOTON.2009.258)

Hecht - Maiman and 50 years of lasers 47 Hecht - Maiman and 50 years of lasers 48  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

Hecht - Maiman and 50 years of lasers 49  Metamaterials

 Nanophotonics

 Plasmonics

 Photonic crystals

 Microstructured optical fibers

 Open new possibilities

 New classes of optical properties

 Better confinement of light

 Stronger interactions

Hecht - Maiman and 50 years of lasers 50 New facilities: National Ignition Facility

1.8 MJ @355 nm Hecht - Maiman and 50 years of lasers 51 Linac Coherent Light Source Free-electron laser 0.15-1.5 nm

Hecht - Maiman and 50 years of lasers 52  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

Hecht - Maiman and 50 years of lasers 53  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

Hecht - Maiman and 50 years of lasers 54 Physics Today Oct 2007

Hecht - Maiman and 50 years of lasers 55