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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.

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a charles townes legacy
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
Dartmouth College

An Ivy League School in New England




dartmouth college1
Dartmouth College

4000 undergraduates (# men = # women)

Graduate school in the sciences

Medical school (1797 – fourth oldest)

Tuck Business School (1900 – the first)

Thayer School of Engineering – (1867)

the oldest engineering graduate school

thayer school of engineering
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)
thayer school impact areas
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

optics and lasers at thayer
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

other optics at thayer
Other optics at Thayer

Magneto-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)

biomedical imaging research at thayer
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)

other lasers and optics biomedical research
Other lasers and optics biomedical research

Photodynamic 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)

a townes legacy
A Townes Legacy

Lasers that are everywhere

eg. the laser pointer

laser printer
Laser Printer




cd dvd players
CD/DVD Players

Laser diode



the internet
The Internet

Optical Fiber




Laser Diode

Laser light is focused

into a single fiber

product scanners supermarkets
Product ScannersSupermarkets

Laser scans

across bar

code. Reflected

light, modulated

by the bar code,

is detected, and

data is entered

in a computer.




lasik procedure
LASIK procedure

Laser Light

Laser re-shapes cornea after flap (conjunctiva) is lifted

history from quantum electronics to laser
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

stimulated emission the source of gain
Stimulated Emission: the source of gain

Einstein, 1916


Spontaneous emission

excited state


ground state

More light

leaves than

came in





charles townes and the maser with post doc jim gordon about 1953
Charles Townes and the Maser(with post-doc Jim Gordon) about 1953




Maser requires

gain and feedback


Amplification by


Emission of


Gain requires

Stimulated emission

Result: Oscillation


the laser idea 1958 charles townes and art schawlow
The Laser Idea (1958) Charles Townes and Art Schawlow


as gain



Mirrors for feedback






~ 1963

the first ruby laser 1960 ted maiman at hughes aircraft
The First Ruby Laser: 1960Ted Maiman at Hughes Aircraft

Flash Lamp


Gain: ruby rod excited by light from a helical flash lamp

Mirrors: silver films on the end of the ruby rod


The First Gas Laser – Helium/Neon(Inventors: Javan, Bennett and Herriott)


Gain: helium-neon

gas discharge




multi-layer films

what do today s lasers look like they can be small
What do today’s lasers look like?They can be small …

Laser diodes are tiny chips of semiconductor






The laser diode chip

Used in CD players,

laser printers, and

fiber optic systems

they can be large national ignition facility
They can be large: National Ignition Facility

The world’s largest laser, being built now

A person

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

Lawrence Livermore National Laboratories

capabilities of lasers gain feedback stimulated emission
Capabilities of Lasersgain + feedback = stimulated emission

Coherent (All photons behave in an identical manner)


focus to small point


Ultra-stable single frequency or color (1 part in 1015)

Ultra-high speed communications 1012 bps

Ultra-longdistance communications (to the moon)

Ultra-short pulses 3 attoseconds 10-15 sec

Ultra-high power (for 10-12 s) >1018 W

Ultra-small size 10-12 cm3


All stimulated emission photons are identical, like soldiers

Spontaneous emission photons

are random

U.S. Soldiers, World War II

Time’s Square

New Year’s Eve




directional laser beams reach the moon and back
Directional: Laser beams reach the moon and back

Time delay

of pulses

gives distance

Lasers beams


in straight lines

focus to a small point lasers drill holes smaller than human hair
Focus to a small point: Lasers drill holes smaller than human hair

Hole Size ~50 µm

Hole size ~ 2 µm



Sizes to scale



miniature commercial interferometers
Miniature Commercial Interferometers

Reflective surface


Measurement of distance, motion, non-destructive testing

Non-contact measurement

ultrastable ligo interferometer for measuring gravity waves
Ultrastable: LIGO Interferometerfor measuring gravity waves

near Baton-Rouge Louisana – two arms, each 2.5 mi long


monochromatic ring laser gyro sagnac effect
Monochromatic: Ring Laser Gyro Sagnac Effect

One gyro

Honeywell’s 3-gyro system

Clockwise vs. Counterclockwise

Frequency Difference determines rotation

research at mit 1962 1966
Research at MIT: 1962-1966

Townes moved to MIT in the fall, 1961

Existing 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

lasers enabled nonlinear optics second harmonic generation
Lasers enabled Nonlinear Optics >Second Harmonic Generation<

Laser beam enters a crystal of ADP

as red light and emerges as blue

Electron orbitals distort nonlinearly -- non-linear polarization




w1 + w2



Light Pulse

Electrical Signal

w0 - w0

7670 A

6943 A



wL - W


Representation of the spectrum

Energy difference between photons

is given up to molecular vibrations W

mit laser laboratory 1962 65
MIT Laser Laboratory, 1962-65

Stimulated Raman Scattering

my phd research nonlinear optics stimulated raman scattering
My PhD research: Nonlinear Optics Stimulated Raman Scattering

Laser  Stokes + molecular vibration

A nonlinear process

that introduces

new wavelengths by


molecular vibrations

Stokes beam

wL + W

wL - W



Laser beam

Two Laser Photons



Molecular vibration + Laser  anti-Stokes

Anti-Stokes radiates in rings

driven by Stokes in corresp. ring

First explanation of

multi-photon processes in

Stimulated Raman Scattering.

First explanation of anti-Stokes and several orders of Stokes

First explanation of angular

emission of anti-Stokes

proof of coherent molecular vibration theory chiao stoicheff and townes srs in calcite
Proof of coherent molecular vibration theory:Chiao, Stoicheff and Townes: SRS in calcite
my experimental srs data in liquids
My Experimental SRS Data in Liquids

Most of

my results




with theory

Ultimately explained by the presence of self-trapping

townes new idea stimulated brillouin scattering
Townes’ New Idea:Stimulated Brillouin Scattering

Experiments in quartz with Chiao and Stoicheff (PRL May 1964)

my data on stimulated brillouin scattering appl phys lett august 1964 experiments in liquids
My Data on Stimulated Brillouin ScatteringAppl Phys. Lett. August, 1964 experiments in liquids
















Light to

Form its






Power is


self trapping of optical beams
Self-trapping of Optical Beams







No Pinhole

Garmire, et. al. PRL, 1966

How they looked then (1966)

Charles Townes

Frances Townes

ultra short pulses 1966 1970 picoseconds
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, Laussade



integrated optics 1970
Integrated Optics (~1970)

Equivalent to integrated electronics

On one chip: laser, detector, modulator, switch

Uses waveguides


Turns light on

and off

with voltage


Output Light

Input Light

Yariv, Hall

semiconductor waveguides
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

distributed feedback lasers
Distributed Feedback Lasers

Regular Laser


Corrugation replaces end mirrors

Caltech: A. Yariv et al.

laser art
Laser Art



Laserium: laser light show

Laser Light Wall

Caltech Moon Landing Celebration

on tv at art opening 1970
On TV at art opening, 1970


Show of photographs

and light box

Hollywood, 1969

moved to usc in 1975 infrared waveguides with mike bass
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

a typical usc laser laboratory
A typical USC laser laboratory



Susan Allen

~ 1982

lithium niobate modulators
Lithium Niobate Modulators

Lithium Niobate Crystal sliced into wafers & polished

Early modulators were long






Titanium in-diffusion

hybrid optical control optical bistability optically addressed switch
Hybrid Optical Control:Optical BistabilityOptically Addressed Switch



Beam splitter






J. Marburger

S. D. Allen

distributed feedback bistability
Distributed Feedback Bistability

H. Winful, J. Marburger

Output A


Output B

Low intensity light reflects -- high intensity goes through

Control signal can change the direction of the output signal



Recent results from Japan (2004)

all optical bistability
All-Optical Bistability

Nonlinear Fabry-Perot in Semiconductors

Thin sandwich of semiconductor between mirrors as “bread”

C. D. Poole




usc laboratory with researchers
USC Laboratory with Researchers

Alan Kost

Randy Swimm

~ 1988

Semiconductor Quantum WellsNonlinear Optical Properties




Kost, Dapkus, et al.


Quantum Well Hetero-n-i-p-i’s

for sensitive nonlinearities

Experimental Results

mW optical power levels

Band diagram

Kost, Dapkus

some of my usc students
Some of my USC Students

Nan Marie Jokerst

Ramadas Pillai

Boo Gyoun Kim

my students are townes grand students where are they now
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, Professor

Alan 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

  • SongSil Univ. Korea
  • Chaio Tung Univ. Taiwan
  • Japanese Defense
  • Academy
  • Frederick Institute of
  • Technology,Cyprus

Nan Marie Jokerst, Duke University.

J.A. Jones Distinguished Professor

Best Teacher in EECS

Fellow: OSA, IEEE

9 professors

where are townes grand students now
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 year

Original government investment: $5 M.

where are other of his grand students
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)
my women minority students post docs
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
where are my dartmouth graduates now
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
at dartmouth lasers to remove graffiti continued from usc
At Dartmouth: Lasers to Remove Graffiti(continued from USC)


Pattern Recognition

and Computer Controller

YAG laser


Scanning mirror


photo refractive four wave mixing
Photo-refractive Four-wave Mixing




Converts image from one laser beam to another

Can convert color, or direction, or incoherent to coherent

Used for image processing – correlation

Requires semiconductor quantum wells

Competition from computers

Akheel Abeeluck

Referenceless Optical Detectionof Surface Vibrations

Spatially moving speckle









Four-point Photoconductive Detector

Philip Heinz

Detector Array

Summing Electronics

Jon Bessette: Researching ways to extend

the idea to higher frequencies

research now underway optical beam propagation with spatial phase jumps
Research Now UnderwayOptical Beam Propagation with Spatial Phase Jumps

Gaussian Beam

Phase 0

Phase p

Phase p

Phase 0

Ashifi Gogo

At 175 meters

a townes legacy1
A Townes’ Legacy

Lasers, 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

The End

laser research science or engineering
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
scientific advances using lasers
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

  • 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