Potassium Titanyl Phosphate
KTiOPO4, KTP
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Structural and Physical Properties
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Crystal Structure
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Orthorhombic, space group Pna21, point group mm
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Cell parameters
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a = 6.404 Å b = 10.616 Å c = 12.814 Å Z = 8
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Melting Point
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1172 °C incongruent
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Curie Point
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936 °C
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Mohs hardness
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≈ 5
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Density
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3.01 g / cm³
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Color
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Colorless
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Hygroscopic susceptibility
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No
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Specific heat
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0.1643 cal / g• °C
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Thermal conductivity
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0.13 W / cm / °K
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Electrical conductivity
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3.5 x 10-8 s/cm (c-axis, 22°C, 1 KHz)
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Nonlinear Optical Properties
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Phase matchable SHG range
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497 – 1800 nm
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Nonlinear optical coefficients
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d31 = 6.5 pm / v d32 = 5 pm / v d33 = 13.7 pm / v d24 = 7.6 pm / v d15 = 6.1 pm / v deff(І?І?) ≈(d24 – d15) sin2fsin2q - (d15sin²f + d24cos²f) sinq
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For type II SHG of a Nd: YAG
Laser at 1064 nm
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Pm angle: q = 90°C, f = 23.3° Effective SHG coefficient: deff» 8.3 xd36 (KDP) Angular acceptance: 20 mrad-cm Temperature acceptance: 25 °C-cm
Spectral acceptance: 5.6 Å –cm Walk-off angle: 4.5 mrad (0.26°) Optical damage threshold: > 450 MW / cm², (@ 1064 nm, 10 ns, 10 Hz)
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Electro – optic coefficients
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Low frequency (pm/V)
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High frequency (pm/V)
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R13
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9.5
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8.8
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R23
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15.7
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13.8
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R33
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36.3
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35.0
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R51
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7.3
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6.9
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R42
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9.3
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8.8
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Dielectric constant
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Eeff= 13
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Optical properties
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Transmitting range:Density
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350 – 4500 nm
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Refractive indices 1064 nm 532 nm
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nx 1.7377 1.7780
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ny 1.7453 1.7886
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nz 1.8297 1.8887
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Sellmeier equations
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nx2 = 3.0065 + 0.03901 / (l2 - 0.04251) – 0.01327 l2 ny2 = 3.0333 + 0.04154 / (l2 – 0.04547) – 0.01408 l2 nz2 = 3.0065 + 0.05694 / (l2 – 0.05658) – 0.01682 l2
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Therm – optic coefficients
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dnx / dT = 1.1 x 10-5 / °C dny / dT = 1.3 x 10-5 / °C dnz / dT = 1.6 x 10-5 / °C
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Absorption coefficient
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αa < 1% cm-1 @ 1064 nm and 532 nm
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