Dr. Howard Schlossberg presents and overview of his program - Lasers and Optics - at the AFOSR Spring Review 2012.

1. Lasers and Optics
07 MAR 2012
Howard Schlossberg
Program Manager
AFOSR/RSE
Integrity  Service  Excellence Air Force Research Laboratory
9 March 2012 DISTRIBUTION A: Approved for public release; distribution is unlimited. 1

2. 2012 AFOSR SPRING REVIEW
2301A PORTFOLIO OVERVIEW
NAME: Dr. Howard Schlossberg
BRIEF DESCRIPTION OF PORTFOLIO:
RESEARCH IN LASERS, OPTICS, AND THEIR APPLICATIONS
LIST SUB-AREAS IN PORTFOLIO:
- LASERS
- NON-LINEAR OPTICS
- LASER-MATTER INTERACTIONS
- MICRO-SYSTEMS
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3. Anthony E. Siegman
1931 - 2011
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4. Anthony E. Siegman
1931 - 2011
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5. Anthony E. Siegman
1931 - 2011
•Invention of Unstable Resonator – 1965
•Keeper of the Modes
•Invention of M2 - 1990
•Ultrashort Pulse Measurements
Tony Wrote the Book on
Lasers
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6. LASERS
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7. Portfolio Summary (Detail)
• High Average Power Solid-State Lasers
• Ceramic Laser Solid-State Materials
• Fiber Lasers
• Thin Disk Semiconductor Lasers
• X-PALS
• Modest Power Lasers
• Mid-Infrared Semiconductor Lasers
• Mid-Infrared Fiber Lasers
• Nonlinear Optics
• Nonlinear Frequency Conversion
• Ultrashort Pulses
• Extreme Light
• High Harmonic Generation
• Mid-and Long Wave Frequency Combs
To Dr. Parra
• X-Ray Imaging
• Micromachining
• Microplasma Arrays
• Specialized Lighting
• Plasma chemistry
• Plasma transistor
• RF modulation, protection (DARPA) 7
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8. AFOSR Study of 6.1 Opportunities in High
Energy and High Power Lasers
• Ceramic Solid-State Laser Materials
• Spatially Varying Index and Doping Concentration
• Non-Isotropic hosts
• Fiber Lasers
• Ultra-short, Ultra-Intense Pulses
• Matter Interactions, Propagation, X-Ray Beams
• Integrate with HPL JTO Programs
High Energy Solid-State, and Some Gas, Lasers Today
are an Exercise in Mode Conversion
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9. AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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10. AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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11. Ceramic laser gain media offer a number of important
advantages over single crystals and glasses
:
• Ceramic media can be fabricated with arbitrary shapes and size.
• Ceramics are well suited to produce composite gain media,
consisting e.g. of parts with different doping levels, or even different
dopants
• Spatially varying doping profiles are relatively easily possible. These
aspects give additional freedom in laser design.
• Significantly higher doping concentration can be achieved without
quenching effects degrading the laser efficiency.
• Some materials, e.g. sesquioxides are very difficult to grow into
single crystals, and much easier to obtain in ceramic form.
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12. Ceramic Solid-State Laser Materials
Program Examples
• Ikesue (JTO, Dr. Caster)
– Processing, diagnostics
– Navy does characterization, lasing (Shori)
• Ballato - Clemson (JTO, Dr Sayir)
– Sesquioxides
• Byer – Stanford (JTO, AFOSR)
– Nd, Yb, Tm doped ceramics, Tm fibers
– Works with U. Central Florida (Gaume)
• Wu – Alfred University (AFOSR YIP)
– Yb doped Sr5(PO4)3F (Yb:S-FAP)
• Excellent properties as laser host
• Prototype uniaxial material
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13. AFOSR Sponsored Ceramic Research Meeting in Nagoya
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14. AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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DISTRIBUTION A: Approved for public release; distribution is unlimited.

15. DPALS (Cesium)
There is no requirement that the
pumping frequency be much higher
than the frequency emitted as long as
the difference in frequency is much
greater than kT/h, which can assure
the possibility of negative
temperatures.
Schawlow and Townes, Phys. Rev.
112, 1940 (1958).
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16. XPALS SYSTEM: Cs-Ar
14 Cs-Ar
2 
B  Δε
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Energy (10 cm )
-1
2
6 P
10
3
~837 nm
852.1 nm
1
2
2  6 S
0 X 
4 5 6 6 7
Interatomic Distance (Å)
Continuous tunability between 4, 3, and 2 level systems
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17. XPALS SUMMARY
• The extracted decay constants from laser
excitation spectra yield transition region
slope of -3/2 kT
• ~0.7 kT is a critical value of the energy
separation between adjacent laser levels
• 4 level laser system collapses in a kT
interval of ~ 2 meV
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18. AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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DISTRIBUTION A: Approved for public release; distribution is unlimited.

19. PHOTONIC BANDGAP GAS LASERS
•Diode-pumped gas laser
•Long interaction length allows small absorption
•Enhanced efficiency possible through V-V collisions
•Large mode area or coherent coupling possible
•Corwin - Kansas State U
• U. New Mexico
•University of Bath 20
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20. C2H2 Laser Spectrum and Transitions
Energy states
Potential Lasing States
v1+v3 600
~ 3.1 m
Spectral Intensity (arb. units)
C2H2 Pressure = 111 torr
1.7 m 500
Actual Wavelengths:
~1.5 m
v1 400
v3 3114.6 nm, R(11)
~ 3.8 m
3172.4 nm, P(13)
~ 3.8 m
300 Herman, J. Chem. Ref. Data 32, (2003).
v2
8 m
v5 200
13 m v4
Vibrational ground state
00000 100
ν1 H C C H 0
3.113 3.114 3.115 3.171 3.172 3.173
ν3 H C C H
Wavelength (m)
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21. AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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DISTRIBUTION A: Approved for public release; distribution is unlimited.

22. T. Carmon, Univ. Michigan
Objective: Continuous-in-Time Micro-Emitter at the Extreme UV
Concept:
1) Nonlinear medium
Xenon gas
2) Optical Enhancement by
IR recirculating in a micro-resonator
Local enhancement by metal (Orange)
Compact cw telecom source, no meter-scaled pulsed lasers
3) Indications for High Harmonics
UV detection with an optical spectrum analyzer
Free Electron detection via current monitoring between electrodes
Compact CW IR -e XUV
Laser pump
UV
Xe +
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DISTRIBUTION A: Approved for public release; distribution is unlimited.

23. Tal Carmon, Univ. Michigan
Accomplishments: continuous 4th-Harmonic Generation
UV Extreme UV
results
Past
3rd Harmonics & 3rd-order sum-frequency
generation (separately measured during
Experimentally Demonstrated: different experiments, Nature Phys. 2007)
–UV 4th-harmonic generation [Opt. Exp. 2011]
– Laser emission with incoherent pumping [Adv.
Mater. 2011]
This year
–HyperRaman emission (two-photon-excited
analog of Raman) [Appl. Phys. Lett. 2012,
accepted]
•Theoretically analyzed: Continuous-in-time pump, 2nd-, 3rd-, & 4th-
–An atom-plasmon-resonator system [New J. harmonics emission. Opt. Exp. 2011
Phys., To be submitted]
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Papers are in collaboration with Cohen, Bartal (Technion), Jarrahi (U of M), Rotschild & Baldo (MIT)
DISTRIBUTION A: Approved for public release; distribution is unlimited.

24. AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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25. Laser Locking for Short Pulse Generation
• Pulse synthesis with wavelength and coherent beam combining integrated
into single setup
– Wavelength beam combining controls frequencies
– Coherent beam combining is implemented with feedback from single-phase sensitive
metric
• Advantages
– Scalability
– Reconfigurability
– Large pulse energies, high repetition rates, short optical pulses
– Pulse generation in laser systems, or spectral regions where difficult
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26. Laser Locking
This work
Individual phase Single metric
measurement measurement
f 1, f c f 1, f c
f 2, f c f 2, f c
fn, fc fn, fc
f 1 f 2f n J(f1 f2…fn)
Feedback Feedback
• Feedback is based on single phase sensitive metric
– Allows control of large arrays!
• Stochastic parallel gradient descent algorithm is used for feedback
– Determine performance metric and apply random changes to all inputs
– Update parameters with stochastic gradient
u n1  u n   n J n u n
j j j j
– Vary current to laser arrays to cause phase shift from thermally induced
index of refraction change
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DISTRIBUTION A: Approved for public release; distribution is unlimited.

27. AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography (OCT)
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DISTRIBUTION A: Approved for public release; distribution is unlimited.

28. Dual-comb FT spectroscopy
GaSe
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DISTRIBUTION A: Approved for public release; distribution is unlimited.

29. AGENDA
• Ceramic Solid-State Lasers
• X-Pals, Three Level Lasers
• Photonic Bandgap Gas Lasers
• Ultraviolet Harmonic Lasers
• Multiple Line Pulsed Lasers
Technology Transfer Examples
• Infrared Short Pulse FTIR
• Optical Coherence Tomography
(OCT)
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DISTRIBUTION A: Approved for public release; distribution is unlimited.

30. Optical Coherence Tomography (OCT)
• Invented with AFOSR funding
• Very broad-based optical
diagnostic technique.
• Expanded under program to
include Doppler and polarization-
sensitive OCT.
• Recent breakthroughs in speed –
spectral and swept source OCT –
and resolution.
• Military examples:
– Burn depth measurement.
– Blood flow.
– Airway damage.
• Civilian spin-off examples:
– Eye problems.
– Coronary artery disease
– Barrett’s Esophagus.
• Over 16 million eye diagnostics in 2010
• Over 50 thousand coronary artery 33
procedures to date DISTRIBUTION A: Approved for public release; distribution is unlimited.

31. Problem: High mortality from smoke
Inhalation Injury
• 27% of Army burn admissions suffer inhalation injuries
• 10 times greater mortality than other burn patients
• No technology for early diagnosis
Solution: OCT imaging enables early detection
Airway - normal
Inflammation following smoke
inhalation
Advances in speed of OCT imaging and
unique optical probe design enables high
resolution 3D airway imaging
Status: Clinical trials proposed for USAISR & BAMC 34
DISTRIBUTION A: Approved for public release; distribution is unlimited.

32. Artery Wall
Lipid
Intracoronary OCT Calcium
Macrophages
Stent
3D OCT of Human Coronary Artery in vivo
• Next major intracoronary imaging modality
• Identifies plaques before heart attack
• Guide stent intervention
• 3 major companies
• Over 50,000 patients imaged

33. Thank you
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