Nd:YAG Ceramic Laser

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NdYAG Ceramic Laser
Presented by Jeanie McGuire On behalf of Xudong
Sun and C.T. Tsai Florida Atlantic
University Boca Raton, Florida
Florida Research Consortium Tech Transfer
Conference St. Petersburg, Florida - May 17-18,
2004
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NdYAG Ceramic Laser - Team

• Dr. C.T. Tsai, Professor
• Florida Atlantic University, Boca Raton, FL
  since 1990
• Wright Patterson AFB Researcher 1988-90
• Ph.D. Engineering Mechanics-University of
  Kentucky 1985
• Dr. Xudong Sun
• Northeastern University, China, since 1993
• Ph. D. Materials Science and Engineering
• University of Surrey, UK 1993

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NdYAG Laser - Materials

• NdYAG Single Crystals
• most widely used solid-state laser material
• synthesized by conventional Czochralski method
• Problems
• difficult to produce large size crystals
• difficult to push luminescence higher
• limits on high power-output applications
• grown in expensive iridium crucible
• 4-6 weeks to grow

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NdYAG Laser - Materials

• Polycrystalline NdYAG Ceramics
• revolution in solid-state laser material - 1995
• good scaling to aperture size
• higher Nd concentration
• ease of fabrication
• less expensive to produce
• can be mass produced
• Problems
• Light scattering sources from
• Grain boundaries
• Pores
• Composition gradients
• High transparency difficult to achieve

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NdYAG Ceramic Laser - Technology
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FAU NdYAG Ceramic Laser Material- Technology

• Novel urea homogenous precipitation method
• Novel co-precipitation method
• Novel seeding technique

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FAU NdYAG Ceramic Laser Material -
Technology
YAG nanopowder produced by a co-precipitation
method (TEM)

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FAU NdYAG Ceramic Laser Material Technology
Microstructure of the YAG ceramics with 0.5 WT
TEOS (a) sintered at 1700?C (b) sintered at
1650?C (c) sintered at 1600?C.
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FAU NdYAG Ceramic Laser Material Technology
Urea precipitation process for synthesis of YAG
nanopowder

Urea
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FAU NdYAG Ceramic Laser MaterialTechnology

• Co-precipitation process for
• the synthesis of YAG nanopowder.

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FAU NdYAG Ceramic Laser Material- Advantages

• polycrystalline ceramic YAG rods made 2x length
• of maximum single crystals with multi kW
  level or
• 10 kW level high power output
• NdYAG nanopowders with
• narrow size distribution
• good chemical homogeneity
• no hard agglomeration
• high NdYAG content (gt5at) for microchip
• laser applications
• transmittance 80 (similar to single crystal
• optical properties)
• ease of fabrication and mass production

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FAU NdYAG Ceramic Laser Material - Advantages
Dense and fully transparent ceramics produced by
sintering the FAU YAG nanopowders
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FAU NdYAG Ceramic Laser Material - Advantages

FAU YAG ceramic sintered at 1700C is
homogeneous in microstructure and chemical
composition.
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FAU NdYAG Ceramic Laser Material Advantages
Grain size distribution of the YAG ceramic
sintered at 1700?C, average grain size is 12 ?m.
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FAU NdYAG Ceramic Laser Material Advantages

• YAG forms without intermediate YAM and YAP phases
• YAG forms completely at 1000C, 600C lower than
  conventional
• Fabrication of transparent ceramics using wet
  chemical
• processing and solid state reaction method
• Novel nanoseeding technique solves aggregation
  problem for
• nanopowders obtained at temperatures over
  1100C
• Defect-free NdYAG ceramic laser rod
• Self- produced nanopowder by vacuum sintering

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FAU NdYAG Ceramic Laser Material - Advantages
X-ray diffraction profiles of the precursors
heated at different temperatures (AHC method).
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FAU NdYAG Ceramic Laser Material- Advantages

? 0.5 wt TEOS ? 0 wt TEOS
Relationship between linear shrinkage and
temperature
Relative density as a function of temperature.
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FAU NdYAG Ceramic Laser Material - Commercial
Uses

• laser systems in fighter planes and satellites
• active remote sensing
• laser target designation
• highly accurate range-finder
• active imaging
• laser systems for guided missiles and bombs

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FAU NdYAG Ceramic Laser Material - Commercial
Uses (continued)

• optical communication
• power beaming
• battle damage assessment
• medical laser surgery
• microchip laser crystals
• metal processing
• semiconductor processing
• . plus 454 kinds of commercial YAG lasers

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FAU NdYAG Ceramic Laser Material - Market Size

• 20M domestic market
• steady annual growth since early 1990s.

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FAU NdYAG Ceramic Laser Material -Target
Industries

• military sector
• commercial laser manufacturers
• source and system suppliers such as Spectra
  Physics, Electox Banblys control Laser Coherent
  Inc etc.
• replacement parts such as Schott Inc Parker
  Hannifin Laser Excel etc.

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FAU NdYAG Ceramic Laser Material- Technology
Status

• Dense and fully transparent YAG ceramics produced
• Highly sinterable YAG nanopowders using a novel
• chemical co-precipitation method have been
  produced
• YAG ceramic sintered at 1700 ?C has optical
  transmittance
• of 63 in visible light wavelengths and 70
  in infrared
• wavelengths.

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FAU NdYAG Ceramic Laser Material- Technology
Status(continued)

• Transmittance is higher than those of others
  under the same
• sintering temperature, but lower than YAG
  ceramics sintered at
• 1800?C.
• IP Provisional patent has been filed
• Commercialization strategies will begin when
  current phase completed.

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FAU NdYAG Ceramic Laser Material - Next Steps

• Further research to better understand
• shrinkage
• grain growth
• effect of Nd on densification
• pore elimination
• effect of SiO2
• direct formation mechanism of YAG
• thermodynamic analysis of YAG phases

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FAU NdYAG Ceramic Laser Material - Next Steps
(continued)

• Objective dope 5 at. Nd into YAG and maintain
  (80) at same time
• Cost estimated 900,000 for
• New sintering equipment
• Labor post docs, faculty, grad students
• Time 3 years of labor and research
• Funding requested as part of DOD SBIR grant
• Results will be the new ceramic crystal

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FAU NdYAG Ceramic Laser Material
For further information today contact Jeanie
McGuire or Steve Nappi at the FAU Booth
After the conference call Dr. C.T. Tsai at
561-297-2824 or tsaict_at_fau.edu
Florida Atlantic University