a charles townes legacy
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A Charles Townes Legacy. Elsa Garmire Sydney E. Junkins Professor of Engineering Sciences Thayer School of Engineering Dartmouth College Townes’ PhD student (1962-1965). Dartmouth College. An Ivy League School in New England. Maine. Dartmouth. Boston. Dartmouth College. - PowerPoint PPT PresentationTRANSCRIPT
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A Charles Townes Legacy
Elsa Garmire
Sydney E. Junkins Professor
of Engineering Sciences
Thayer School of Engineering
Dartmouth College
Townes’ PhD student (1962-1965)
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Dartmouth College
*NH
VT
Dartmouth
An Ivy League School in New England
Maine
Boston
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Dartmouth College
4000 undergraduates (# men = # women)
Graduate school in the sciencesMedical school (1797 – fourth oldest)
Tuck Business School (1900 – the first)
Thayer School of Engineering – (1867)the oldest engineering graduate school
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Thayer School of Engineering
• No separate departments• Synergy across expertise from different engineering disciplines • Teamwork and entrepreneurship are encouraged• Opportunity to take courses with Tuck Business School professors • Opportunity for collaborative research with Dartmouth Medical School• Opportunity for collaborative research with the Science Departments• Graduate Enrollment: 47 PhD students
20 MS students (with research thesis)
60 Masters in Engineering Management (with industrial project)• Undergraduate Enrollment: 112 juniors and seniors• 44 Bachelor in Engineering students (5th year for ABET credit)
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Thayer School Impact Areas• Engineering in Medicine Addresses today's technology-driven healthcare system. Advances
depend in the technical side of patient care. Collaboration between Dartmouth engineers, medical researchers, and clinicians speeds testing and implementation of technological advances.
• Energy Technologies Crucial to the future stability of human society. Research includes a range of projects—from biomass processing to power electronics optimization. Investigators synthesize ideas and expertise from biochemical and chemical, electrical, and materials engineering as well as physics, chemistry, and microbiology.
• Complex Systems Systems permeate technology in the 21st century. The goal is to
analyze and design complex systems so that their behavior can be predicted and controlled. Dartmouth engineers are working together to meet the challenges of large, complex engineered systems such as computer networks, social networks, smart robots, living cells, energy infrastructure, and the near-Earth space environment.
Source: http://engineering.dartmouth.edu/research/index.html
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Optics and Lasers at Thayer• Instrumentation A new type of non-contact optical sensor of
vibration and other motion detection. New designs for free space optical communications, both for transmission through the atmosphere and through water. Active and passive waveguides for optical signal processing, telecommunications, optical data storage, and other applications. Fiber optics devices such as tunable filters and fiber lasers. (Faculty contact: Garmire)
• Femtosecond pulses being transmitted through water sustain much less loss than longer pulses, particularly at long distances. Femto-second pulses are used to create terahertz radiation, whose transmission through a variety of media is being investigated. (Faculty contacts: Osterberg, Garmire)
• Nonlinear optical studies investigate second- and third-order nonlinear effects in optical glass fibers, thin films, and semiconductor structures. A novel project is ultrafast pulse shaping of wavelets for high bandwidth fiber-optic free-space systems. Nonlinear devices are being investigated for high-speed image processing and for time-to-wavelength conversion for communication systems. (Faculty contact: Garmire, Osterberg)
Source: http://engineering.dartmouth.edu/research/by-discipline/electrical.html
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Other optics at ThayerMagneto-optics: production and studies of magnetic vortex states in ring
structures, and the coupling between them. Thin dielectric films enhance the magneto-optic Kerr effect signal. Interactions of proximal rings and symmetry effects. (Faculty contact: Gibson)
Nanophotonics: interaction of light with sub-micron structures and nano-textured materials. Molecular Imprint Polymers (MIPS) with surface plasmon resonance and capacitive measurements for chemical sensing. Applications include the detection of pollutants, chemical residues and biological compounds indicative of early-stage cancer. ZnO nanopillars for photonic bandgap engineered devices. (Faculty contact: Gibson)
Microelectromechanical Systems (MEMS) -- includes modeling, fabrication, and testing of the following:
– untethered mobile micro-robots, and interactions between small swarms of micro-robots;
– stress engineering of out-of-plane electromechanical structures such as microturbines;
– integrated micro-inductors for power electronics; – high sensitivity optical sensors; – binary optical devices.
MEMS device fabrication takes place in Thayer School's microengineering lab, a Class 100 clean room facility. (Faculty contact: Levey)
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Biomedical Imaging Research at Thayer Fluorescence imaging to track molecular signals and tags in tissue, especially cancer tumors
in vivo and vascular diseases. Also coupled to magnetic resonance imaging and computed tomography imaging. Evaluating their response to therapy. (Faculty contact: Pogue)
Dynamic multimodal imaging (DMI), a framework for reconstructing images of neural and vascular dynamics in the human brain. DMI combines concurrently recorded data from multiple imaging modalities such as electroencephalography, near-infrared spectroscopy, and functional magnetic resonance imaging. (Faculty contact: Diamond)
Image-guided neurosurgery gives the surgeon the ability to track instruments in reference to subsurface anatomical structures. Using clinical brain displacement data, a computational technique is being developed to model the brain deformation that typically occurs during neurosurgery. The resulting deformation predictions are then used to update the patient's preoperative magnetic resonance images seen by the surgeon during the procedure. (Faculty contact: Paulsen)
Near-infrared imaging (NIR) to quantify blood and water concentrations in tissue, as well as structural and functional parameters. NIR spectroscopy can be combined into standard imaging systems to provide additional information for breast cancer detection and diagnosis. Work is ongoing to improve techniques for better image reconstruction, display and integration with magnetic resonance imaging (MRI) and computed tomography (CT) imaging. (Faculty contacts: Pogue, Paulsen, Jiang)
Non-linear image reconstruction techniques: Excitation-induced measurements from each instrument are compared with calculations to compute images. As images are updated in a non-linear iterative process, important features become more apparent. The computational core of the breast imaging project works synergistically to improve our fundamental understanding of these mathematical systems to improve overall image quality and resolution. These processes have been developed for both 2D and 3D geometries in each modality and are being expanded to exploit emerging parallel computing capabilities. (Faculty contacts: Paulsen, Meaney)
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Other lasers and optics biomedical researchPhotodynamic therapy for cancer, age-related blindness, pre-malignant
transformation or psoriasis. Administration of a photosensitizing agent, together with the application of moderate intensity light activates the molecules to produce local doses of singlet oxygen. Developing dosimetry instrumentation and software, fluorescence tomography imaging to sense drug localization, and assaying treatment effects in experimental cancers. (Faculty contacts: Pogue, Hoopes)
Therapy monitoring using imaging modalities. These include:– near-infrared imaging of brain tissue; – near-infrared spectroscopy for diagnosing peripheral vascular disease; – electrical impedance spectroscopy for radiation therapy monitoring; – magnetic resonance elastography for detecting brain or prostate lesions; to
follow the progression of diabetic damage in the foot; – microwave imaging spectroscopy for hyperthermia therapy monitoring, brain
imaging, and detection of early-stage osteoporosis. (Faculty contacts: Paulsen, Meaney)
Clinical optical-electric probes are being developed for noninvasive simultaneous measurement of blood oxygenation and electrical potential changes associated with brain activity. (Faculty contact: Diamond)
Label free genome sequencing to "read" the sequence in a single DNA molecule in a massively-parallel fashion. The technology combines concepts of single nucleotide addition sequencing, near field optics, single molecule force spectroscopy, and microfluidics. (Faculty contact: Shubitidze)
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A Townes LegacyLasers that are everywhere
eg. the laser pointer
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Laser Printer
http://library.thinkquest.org/C0115420/Cyber-club%20800x600/Gif/pics2/Laser%20Printer.gif
Laserdiode
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CD/DVD Players
Laser diode
Lens
CD
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The Internet
Laser Diode
Optical Fiber
MultipleOptical Fibers
Laser light is focusedinto a single fiber
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Laser scansacross bar code. Reflected light, modulatedby the bar code,is detected, anddata is entered in a computer.
Handscanner
Product ScannersSupermarkets
Photo-Detector
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Hologram for Security Credit Card, ID Cards, Advertising
November, 1985
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LASIK procedure
Laser re-shapes cornea after flap (conjunctiva) is lifted
Laser Light
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History:From Quantum Electronics to Laser
• Combine physics of “quantum” with electrical engineering of “electronics”
• Developed after WWII
• Microwave devices, originating from radar
• Charles Townes: designed/built radars
then studied microwave spectroscopy
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Stimulated Emission: the source of gain
http://www.thetech.org/exhibits/online/lasers/Basics/images/albert.gif
http://www.physics.ubc.ca/~outreach/phys420/p420_95/mark/h2.gif
Stimulatedemission
Spontaneous emissionAbsorption
Einstein, 1916
photon
ground state
excited state
More light leaves than came in
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Charles Townes and the Maser(with post-doc Jim Gordon) about 1953
http://globetrotter.berkeley.edu/people/Townes/images/maser.jpg
Maser
Townes
Gordon
Maser requires gain and feedback
Gain requiresStimulated emission
MicrowaveAmplification byStimulatedEmission ofRadiation Result: Oscillation
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Oscillation from gain and feedbackExample: sound systems
Speaker
Microphone
Amplifier
Feedback Gain
Result: a shriek!!
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The Laser Idea (1958) Charles Townes and Art Schawlow
Townes
Schawlow
ArgonLaserBeam
Atoms as gainmedium
Mirrors for feedback
~ 1963
gain
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The First Ruby Laser: 1960Ted Maiman at Hughes Aircraft
http://www.ieee-virtual-museum.org/media/bW8Jx8FS8nF2.jpg
Ruby
Flash Lamp
Gain: ruby rod excited by light from a helical flash lampMirrors: silver films on the end of the ruby rod
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The First Gas Laser – Helium/Neon(Inventors: Javan, Bennett and Herriott)
Gain: helium-neongas discharge
Mirrors:Special high-reflectivitymulti-layer films
1961
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What do today’s lasers look like?They can be small …
http://upload.wikimedia.org/wikipedia/en/thumb/b/bd/Laser_diode_chip.jpg/300px-Laser_diode_chip.jpg
Laser diodes are tiny chips of semiconductor
The laser diode chip
A commercial package
Used in CD players, laser printers, and fiber optic systems
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They can be large: National Ignition Facility
The world’s largest laser, being built now
Lawrence Livermore National Laboratories
View of Laser Bay 1 from the transport spatial filter, containing 96 laser beams.In all, 192 beams of beampath are complete: 1.8 Million Joules of light.
To ignite nuclear fusion
A person
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Capabilities of Lasersgain + feedback = stimulated emission
Coherent (All photons behave in an identical manner)directionalfocus to small pointinterfere
Ultra-stable single frequency or color (1 part in 1015)Ultra-high speed communications 1012 bpsUltra-long distance communications (to the moon)Ultra-short pulses 3 attoseconds 10-15 secUltra-high power (for 10-12 s) >1018 WUltra-small size 10-12 cm3
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Coherence
Time’s SquareNew Year’s Eve
U.S. Soldiers, World War II
http://www.trumanlibrary.org/photographs/58-790-38.jpg
http://www.mistyvisions.com/images/nyc.jpg
All stimulated emission photons are identical, like soldiers
Spontaneous emission photons are random
speckle
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Directional: Laser beams reach the moon and back
Time delay of pulses gives distance
Lasers beams travel
in straight lines
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Focus to a small point: Lasers drill holes smaller than human hair
Hole Size ~50 µmHuman
Hair
Sizes to scale
Hole size ~ 2 µm
OpticalFiber
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Interference
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Miniature Commercial Interferometers
www.armstrongoptical.co.ukReflective surface
Measurement of distance, motion, non-destructive testingNon-contact measurement
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Ultrastable: LIGO Interferometerfor measuring gravity waves
http://www.phys.lsu.edu/dept/gifs/LIGO.gif
near Baton-Rouge Louisana – two arms, each 2.5 mi long
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Monochromatic: Ring Laser Gyro Sagnac Effect
One gyro Honeywell’s 3-gyro system
Clockwise vs. CounterclockwiseFrequency Difference determines rotation
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Interference: Holograms
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Research at MIT: 1962-1966
Townes moved to MIT in the fall, 1961Existing lasers: Ruby laser (pulsed, high
power), HeNe (continuous, monochromatic, invisible)
Fundamental research: Michelson-Morley experiment with HeNe (looking for aether).
Nonlinear Optics with the ruby laser
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Lasers enabled Nonlinear Optics >Second Harmonic Generation<
Laser beam enters a crystal of ADP as red light and emerges as blue
fy.chalmers.se/.../Photonic/information.html
Electron orbitals distort nonlinearly -- non-linear polarization
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00
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21 22
1 + 2
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Light Pulse
Electrical Signal
0 - 0
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6943 A7670 A
SRS Laser
Representation of the spectrumEnergy difference between photons is given up to molecular vibrations
LL -
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MIT Laser Laboratory, 1962-65
Stimulated Raman Scattering
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My PhD research: Nonlinear Optics Stimulated Raman Scattering
A nonlinear processthat introduces
new wavelengths byinvolving
molecular vibrations
Two Laser Photons
Stokes Anti-Stokes
Anti-Stokes radiates in ringsdriven by Stokes in corresp. ring
Molecular vibration + Laser anti-Stokes
Laser beam
Stokes beam
L - L +
L L
Laser Stokes + molecular vibration
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First explanation of multi-photon processes inStimulated Raman Scattering.
First explanation of anti-Stokes and several orders of Stokes
First explanation of angularemission of anti-Stokes
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Proof of coherent molecular vibration theory:Chiao, Stoicheff and Townes: SRS in calcite
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My Experimental SRS Data in Liquids
Agrees with theory
Most ofmy results“Stokes”
“Anti-Stokes”
Ultimately explained by the presence of self-trapping
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Townes’ New Idea:
Stimulated Brillouin Scattering Experiments in quartz with Chiao and Stoicheff (PRL May 1964)
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My Data on Stimulated Brillouin ScatteringAppl Phys. Lett. August, 1964 experiments in liquids
SBSSeveralorders observed
Q-switchgain mirror SBS
Laser
Fabry-Perot Interferogram
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NonlinearRefractiveIndexEnablesLight to Form its Own Waveguide
SpatialSoliton
ThresholdPower isRequired.
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Self-trapping of Optical Beams
Laser
IncreasingLaserPower
No Pinhole
Garmire, et. al. PRL, 1966
Self-trapping
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How they looked then (1966)
Charles Townes Frances Townes
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Elsa, Gordon and Lisa Garmirethe Townes’ horse and buggy
1966
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1966-1974: Research in Amnon Yariv’s Caltech Laboratory
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Ultra-short Pulses (1966-1970)
Picoseconds• How do we generate them?
– Nonlinear absorption in laser cavity: theory
• How do we measure them?– Collide two pulses in two-photon fluorescent medium
• How do we expect them to behave in nonlinear optics?– Harmonic pulses longer in time
Yariv
Comly
Yariv, Laussade
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Integrated Optics (~1970)
Equivalent to integrated electronicsOn one chip: laser, detector, modulator, switch
Uses waveguides
Modulator:
Turns light on
and off
with voltage
VInput Light Output Light
Yariv, Hall
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Semiconductor Waveguides
• Ion Implantation– First demonstration– First use for waveguide couplers– First use for rib waveguides
• Zinc Diffusion– First demonstration
• Epitaxy (growing one layer on another)– First demonstration:
DFB lasers
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Distributed Feedback Lasers
http://www.alpeslasers.ch/technology/dfb_pict_b.jpg
Corrugation replaces end mirrors
Caltech: A. Yariv et al.
Regular Laser
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Laser ArtLaserium: laser light show
Laser Light Wall
Caltech Moon Landing Celebration
LaserBeacon
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On TV at art opening, 1970
LASER IMAGESShow of photographsand light boxHollywood, 1969
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Experiments in Art and TechnologyPepsi-Cola Pavilion, Expo ’70, Japan
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Moved to USC in 1975 Infrared Waveguides with Mike Bass
Infrared light from CO2 lasers cuts materials
Wouldn’t a fiber for this laser be nice?
Our solution: hollow metal waveguide
Rectangular cross-section
Low-loss, flexible in one dimension
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A typical USC laser laboratory
Susan Allen
GraduateStudent
~ 1982
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Lithium Niobate Modulators
http://fibers.org/objects/news/6/11/1/FSErnd1_10-04.jpg
Pencil
Early modulators were long
Lithium Niobate Crystal sliced into wafers & polished
Today’sTinyModulator
Titanium in-diffusion
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Hybrid Optical Control: Optical Bistability Optically Addressed Switch
Laserinput
output
amplifierdetector
Beam splitter
J. MarburgerS. D. Allen
V
Input light
Output light
Hysteresis
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Distributed Feedback Bistability
Recent results from Japan (2004)
. http://mizumoto-www.pe.titech.ac.jp/img/
Control signal can change the direction of the output signal
Input
Output A
Low intensity light reflects -- high intensity goes through
Output B
H. Winful, J. Marburger
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All-Optical Bistability
Nonlinear Fabry-Perot in Semiconductors
Thin sandwich of semiconductor between mirrors as “bread”
InAs C. D. Poole
in
out
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USC Laboratory with Researchers
Alan KostRandy Swimm
~ 1988
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Semiconductor Quantum WellsNonlinear Optical Properties
GaAs
AlGaAs
Pump-Probe Experiments
Kost, Dapkus, et al.
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Quantum Well Hetero-n-i-p-i’sfor sensitive nonlinearities
Band diagram
Experimental Results
Kost, Dapkus
mW optical power levels
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Some of my USC Students
Nan Marie Jokerst
Ramadas Pillai
Boo Gyoun Kim
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The USC Research Group
~ 1990
me
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Marla, Lisa, Elsa, Bob, 1979
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One of the Advantages of being a Researcher
1982
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My students are Townes’ “grand-students”Where are they now?
Former Students now faculty members:
Former Post-Docs now faculty members:Susan D. Allen, VP for Research & Academic Affairs, Arkansas State Ping Tong Ho, University of Maryland, ProfessorAlan Kost, University of Arizona, Associate Professor
Herbert Winful, University of Michigan, Arthur Thurnau Prof.Professor of the Year, EECS (twice)State of Michigan Teaching Excellence Fellow: OSA, IEEE, APS
Nan Marie Jokerst, Duke University. J.A. Jones Distinguished ProfessorBest Teacher in EECS Fellow: OSA, IEEE
•SongSil Univ. Korea•Chaio Tung Univ. Taiwan•Japanese Defense Academy•Frederick Institute ofTechnology,Cyprus
9 professors
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Where are Townes’ grand-students now?• Started companies
– C. Poole, Eigenlight, CTO (10,000 Sq. ft. manufacturing) OSA Fellow
– R. Pillai, Nuphoton, President, $3.4 M annual sales (14th largest Indian-American manufacturer)
– R. Logan, Phasebridge, President ($2 M annual sales)– E. Park, LuxN, CTO (36 employees, bought out)– D. Magharefteh, Azna Inc. Chief Technology Officer– J. Millerd, 4D Technology Corp., CTO (R&D 100, NASA awards)
• Key positions in companies– T. Hasenberg, JDS Uniphase, Director of Wafer Fabrication. – K. Tatah, Cray Inc. Lead Optical Engineer– R. Kuroda, XCOM Wireless, Vice President of Engineering – S. Koehler, Phasebridge, VP of Strategic & Product Marketing– M. Jupina (MBA), Checkpoint Technologies, Sales & Marketing Manager
Total financial impact: ~ $15 M per yearOriginal government investment: $5 M.
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Where are other of his grand-students?• Small start-ups and sole proprietorships
– W. Richardson, Qusemde, CTO. (3 employees)(after research scientist at Stanford)– K. Liu, All-optronics, President (3 employees)– G. Hauser. Sole proprietor, microscopes– J. Menders, IPITEK, Principal Investigator– D. Tsou, consultant
• Government Service– A. Partovi (MBA), The Science Foundation of Ireland, Research Advisor– C. Mueller, Aerospace Corporation, 20-yr award; NASA awardee, 2003 – M. Chang, Aerospace Corporation– K. Wilson, Jet Propulsion Laboratories
• Other– T. Papaiannou, Cedars Sinai Hospital– Erich Ippen, Industrial Light and Magic– M. Yang, retired (raising two children)
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My women/minority students & post-docs
• Katherine Liu Herbert Winful• Nan Marie Jokerst Keith Wilson• Mei Yang Wayne Richardson• Jean Yang Antonio Mendez• Grace Huang
• Susan Allen 13 out of 45: ~1/3• Kate Zachrewska• Cao Mingcui• Patricia Berghold
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Where are my Dartmouth graduates now?
• Ergun Canoglu (PhD, USC), LuxN, Principal Engineer • Akheel Abeeluck (PhD), Directed Energy Solutions,
Principal Investigator• Brian West (MS), Post-doc, University of Toronto • J. Halbrooks (MS), Engineer, Mathsoft• Philip Heinz (PhD), Prismark Partners
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At Dartmouth: Lasers to Remove Graffiti
(continued from USC)
YAG laser
Scanning mirrorcontrol
patented
Pattern Recognitionand Computer Controller
Camera
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Photo-refractive Four-wave Mixing
Converts image from one laser beam to anotherCan convert color, or direction, or incoherent to coherentUsed for image processing – correlationRequires semiconductor quantum wellsCompetition from computers Akheel Abeeluck
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Referenceless Optical Detectionof Surface Vibrations
Philip Heinz
Detector
Spatially moving speckle
Mirror
HeNe laser Detector
Elements
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Four-point Photoconductive Detector
Detector Array Summing Electronics
Jon Bessette: Researching ways to extend the idea to higher frequencies
Philip Heinz
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Research Now Underway
Optical Beam Propagation with Spatial Phase Jumps
Phase 0
Phase 0Phase
Phase Gaussian Beam
At 175 metersAshifi Gogo
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My Family in October, 2005Charles Townes’ 90th Birthday
My Family in October, 2005Charles Townes’ 90th Birthday
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A Townes’ LegacyLasers, which are ubiquitous
• Lasers differ in type, capabilities, and size• Lasers are a fundamentally new technology, operating
on a different principle from anything before.• Government’s investment in my research pays off
annually with my former students.• These students are Townes’ “grand-students.”• Who could have imagined the science and the
applications?Eleven Nobel Prize years – 24 individuals more each year
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Laser ResearchScience or Engineering?
• The laser was a paradigm shift: nothing like it before
• The maser had no practical application
• No clear path from laser to application
• There is a continuum between science and engineering.– New technology requires new science– New technology enables new science
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Scientific Advances using Lasers
• 4 degree black body radiation• High resolution spectroscopy• Femtosecond chemistry• Biology: confocal microscope• Bose Einstein Condensation• Combustion analysis• Aerodynamics• Atomic Force Microscopy (AFM)• Michelson-Morley Experiment: no ether
Eleven Nobel Prize years – more each year 24 individuals – more each year
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Applications
• Lasers and Processing– LASIK, Surgery, Coagulation– Manufacturing: cutting, welding, heat treating– Materials processing: selective reactions
• Lasers and Information – CD players, laser printers, internet, cell
phones
• Lasers and measurement – Surveying, distance, level line, specialty tools