FIBER OPTIC & FIBER LASER HISTORY & AMERICAN OPTICAL Jeff Hecht Author, City of Light: The story of fiber optics Contributing Editor, Laser Focus World

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1841 Colladon's Fountain Total internal reflection

Water-air interface

Guides along parabola Scattering in water Sparkling at turbulence Dark at smooth areas

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Paris fountains at night 1889

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Origins of imaging fiber bundles • Patented 1930, Clarence W. Hansell

• Demonstrated 1930, Heinrich Lamm

• Reinvented after World War II

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Postwar fiber optics

Holger Møller Hansen Harold H. Hopkins

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The Road to AO

A.C.S. Van Heel Brian O'Brien

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A full agenda at AO

Van Heel's bundle Todd-AO Oklahoma

O'Brien Jr, Todd, Fred Zinnermann, O'Brien Sr, Hammerstein

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Brian O'Brien and Will Hicks

Brian O'Brien

• Told CIA that fiber bundles could scramble images

• Did nothing for months • Busy with Todd-AO • Briefed Hicks

•  September 1954 •  gave him 2 plastic-clad fibers

• Went back to Todd-AO

Will Hicks

• Physicist •  Furman U, UC Berkeley

• Working on fibers for Milliken Research Trust •  Textiles, not glass

• CIA hired him for AO • Assignment

•  Make and clad fibers •  Assemble into image

scrambler

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The O'Brien fiber patent Voided because it was filed Nov. 19, 1954. Van Heel paper was published in Holland on 12/6/53 – European style

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Will Hicks at AO

• Validated need for cladding • 'Cover story' medical imaging • Real job image scrambler • Crucible drawn fiber

• Plastic coated • Poor transmission • Double crucible glass clad

• Visits OSA Lake Placid meeting October 1956 • Meets the competition

BOSSES Steve MacNeille Walt Siegmund

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University of Michigan

Basil Hirschowitz Larry Curtiss

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The Cladding Problem

• Møller Hansen – margarine • Van Heel – Beeswax • Hicks/O'Brien – plastic • Michigan – lacquer, plastic • Hicks – double crucible glass • Curtiss – rod-in-tube glass

• Picked fire-polished rods • Excellent quality – Dec 1956 • Needed 40 km of 40-µm fiber to make 40,000-fiber flexible bundle

Cladding essential to prevent crosstalk Needed low-index transparent material But what would work?

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Hicks and the AO approach • Progress stalled • Lee Upton-AO glass

• Collapsing glass tubes onto electrical components

• Frederick Norton, MIT • Millifiore glass

• Stacking fiber, then drawing down

• Rigid bundles • Equipment delays

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Wikipedia art

Image scrambler demonstration • Problems

•  Mechanical polishing •  Contaminants

• Demonstration •  Looped fiber around drum •  Glued one region •  Sawed in half •  Scrambled fibers in middle •  Sawed in half again

•  Encoder/decoder pair •  Shipped to CIA

• Vacation at last! • Myrtle Beach • Hicks realizes codes can

wear out • Tells CIA only 18 uses

• End of project • Switches to faceplates

• Bill Gardner •  Image intensifiers • AO fails to develop

• Hicks launches Mosaic

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Mosaic Fabrications • Fiber-optic faceplates •  Image intensifiers • Fiber tapers • Fiber-optic Christmas tree

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Elias Snitzer joins AO • Former professor at Lowell Tech

• Shown bundle photo •  Identifies patterns as transverse modes

• First single mode fiber • With Hicks, Harold

Osterberg, Michael Polanyi

• Develops mode theory

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Snitzer and glass lasers • Began work in 1960 • Neodymium-doped glass laser: 1961

• Clad glass rods • First fiber laser • First fiber amplifier • Later

• Dual-clad fiber •  1480-nm pumping

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Pioneering research

Dielectric waveguide modes First glass laser, in clad rod (thick fiber)

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Fiber amplifier

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Eli at AO Sep 1964 with big glass laser

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Trends in fiber communications • Charles Kao proposed in 1966 • Corning first low-loss fiber 1970

•  Fiber was single-mode

• Bell Labs wanted multimode early 1970s • Naval Research Lab used SM for sensing early 1970s • Single-mode 'rediscovered' circa 1980

•  British Telecom Research Labs •  Japanese telecommunications companies •  Bell Labs submarine cable group

• Global networks spread 1980s •  Interest in wavelength-division multiplexing •  Optical amplifiers to simplify design

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First revival of fiber laser • End pumping Nd-doped fiber with laser

• First with dye laser • End pump with diode laser

• Prompted by interest in fiber communications

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Doped fiber sensors Demonstrated 1983

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Doped fiber lasers to amplifiers • David Payne at University of Southampton mid-1980s

•  Experiments with doped fibers •  Demonstrates laser action by end pumping with lasers •  Tests many rare earths in lasers •  Demonstrates erbium-fiber laser in 1.55-µm band •  Demonstrates erbium-fiber amplifier in 1.55-µm band

•  Importance of fiber amplifiers •  Optical amplification sought for fiber communications •  Semiconductor optical amplifiers were noisy •  Single-mode fiber zero dispersion wavelength 1.3 µm •  Single-mode fiber minimum loss 1.55 µm

• Needed to be made practical for systems

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Snitzer OFC 88 postdeadline

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Diode pumping at 1480 nm

The importance of fiber amplifiers • Can amplify many wavelengths simultaneously • Allowing wavelength division multiplexing • Multiplying fiber capacity by ~100-fold • Vital for long-distance transmission

•  Submarine cables, continental backbone networks • Developed in early 1990s

•  Just as Internet growth takes off • Fueled growth of Internet and telecommunications • Crucial element of global telecommunications network • Fiber system capacity still growing

•  Spatial division multiplexing, multiple core, multiple modes •  100s of terabits per second per fiber

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Snitzer OFC 89 postdeadline

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Double-clad or dual-core fiber

Evolution of Fiber Lasers • Diode pumping • Dual-core pumping • Erbium fiber lasers

• Communications • Short pulse research • Frequency combs

• Ytterbium fiber lasers •  Industrial lasers • Materials working lasers • High-efficiency lasers

• Advantages • High efficiency • High power • Compact • Reliable

• Applications •  Industrial •  Instrumentation • Research • Medical

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Fiber laser efficiency • Diode pumping

• Converts electric power into pump light efficiently •  ~ 50% electrical to optical efficiency

• Diode matched to absorption line • Optical to optical energy conversion

• Small photon deficit between pump and output • High excitation and extraction efficiency

•  ~ 60-70% optical to optical conversion efficiency

• ~25-35% wall-plug efficiency attainable • Reduces energy requirements • Reduces cooling requirements • Reduces size and weight of laser

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NAVY LaWS (Laser Weapon System)

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Naval Sea Systems Command test integrated with Raytheon PHALANX for ship defense 6 5.5-kW fiber lasers combined to generate 30 kW Shot down UAV in marine environment, reported June 2010

•  Output beam quality BPP~10 M^2~33 •  DC EOE ~ 33% •  Output fiber core diameter 200um •  Output NA ~ 0.09 •  Output fiber length 15m •  Raman level at full power expected to

be ~ -35dB •  Linewidth (FWHM) ~5nm •  Weight ~ 2,500kg •  Size (HxWxD): 1.8m x 2.7m x 0.8m •  Delivered August, 2008 •  Has achieved 50kW in five states and

traveled > 10,000 highway miles

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50-kW multimode fiber laser

IPG photo

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Precision cutting

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IPG Photonics

Femtosecond fiber laser - Calmar • Passively modelocked • Erbium 1530-1565 nm

•  100-500 fs •  1-1000 mW avg •  10-100 MHz

• Er doubled 780 nm •  100 fs, 10-50 MHz •  10-50 mW avg

• Yb 1030-1060 •  100-800 fs, 10-50 MHz •  0.5 mW-5W avg •  Picosecond pulses

compressible

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PolarOnyx single-frequency fiber laser

• Linewidth < 1 kHz • 10-30 dBm output • 1530-1565 nm •  Instrument or module • Applications

•  Fiber gyros •  Metrology •  Coherent communications •  Sensing •  Spectroscopy

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Glass lasers

National Ignition Facility, Lawrence Livermore National Laboratory

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LEGACIES Ideas Inventions Enterprises

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Enterprises • Will Hicks

• Mosaic Fabrications •  Galileo Electro-Optics

•  1984 Inc. •  Set up in old industrial left •  Goal was huge

transmission capacity •  Sold to Polaroid 1982 •  Hicks hired Snitzer to run

company

• Many more

• American Optical • Spun off glass lasers • Continued fiber bundles •  Later sold to Schott

• Fiber amplifiers • Fiber lasers

•  IPG Photonics in Oxford • Many other companies

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Thanks to • Dick Whitney •  IEEE •  IEEE Photonics Society • Richard Linke • Gordon Day • Optical History Museum • Schott North America • Henke-Sass Wolf

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