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Features
KTP crystal is mostly used as nonlinear crystals for frequency doubling of solid-state Nd:YAG crystal or Nd:YVO4 crystal laser, as it has large nonlinear optical coefficients, wide angular bandwidth and small walk-off angle, broad temperature and spectral bandwidth. KTP crystal also has high electro-optic(E-O) coefficient and low dielectric constant, and large figure of merit, these features make it also widely used in electro-optic application.

Advantages of KTP Crystal
Large Nonlinear Optical (NLO) Coefficients
Wide Angular Bandwidth and Small Walk-off Angle
Broad Temperature and Spectral Bandwidth
High Electro-Optic (E-O) Coefficient and Low Dielectric Constant
Large Figure of Merit for an Optical Waveguide Modulator
Nonhygroscopic, Good Chemical and Mechanical Properties
Specifications
Capabilities of KTP Crystal:
Aperture: 2x2 ~ 10x10mm
Lenght: 0.1 - 20mm
Cutting Angle q and f: Determined by different kinds of homonic generartion
Phase matching type: Type I or Type II
End Configuration: Plano/Plano or Brewst/Brewst or Specified

 

Specifications of KTP Crystal:
Angle tolerance: Δθ< ± 0.5°; Δφ< ±0.5°
Dimensional Tolerance: (W ± 0.1mm) x (H ± 0.1mm) x (L + 0.2mm/-0.1mm)
Flatness: <λ/8 at 633nm
Surface Quality: 10/5 Scracth/Dig
Parallelism: < 20 arc seconds
Perpendicularity: < 5 arc minutes
Wavefront Distortion: <λ/8 at 632.8nm
Clear Aperture: Central 95%
Chamfer: 0.15x45°
Coating: a) * S1,S2: AR @ 1064 nm R<0.1% & 532nm R<0.25%
b) * S1:HR @ 1064nm R>99.8% & HT@ 808nm T>95% 
       S2:AR @ 1064 nm R<0.1% & 532nm R<0.25%

 

Properties of KTP Crystal:
Crystal structure Orthorhombic, point group mm2
Melting point 1172°C incongruent
Cell parameters a=6.404Ä, b=10.616Ä, c=12.814Ä, Z=8
Curie point 936°C
Mohs hardness ~5
Density 3.01 g/cm3
Color colorless
Hygroscopic susceptibility no
Specific heat 0.1643 cal/g.°C
Thermal conductivity 0.13 W/cm/°K
Electrical conductivity 3.5x10-8 s/cm (c-axis, 22°C, 1KHz)

 

Transmitting range 350nm~4500nm
Refractive indices - nx ny nz
1064nm 1.7377 1.7453 1.8297
532nm 1.7780 1.7886 1.8887
Absorption coefficients a < 1%/cm @1.064µ m and 0.532µ m
Phase matchable range 0.984 - 3.4 µ m
Therm-optic coefficients dnx/dT=1.1x10-5/°C, dny/dT=1.3x10-5/oC, dnz/dT=1.6x10-5/°C
Nonlinear optical coefficients d31=2.54pm/V, d32=4.35pm/V, d33=16.9pm/V
d24=3.64pm/V, d15=1.91pm/V at 1.064 mm
deff(II)≈ (d24 - d15)sin2φsin2θ - (d15sin2φ + d24cos2φ)sinθ
Electro-optic coefficients - Low frequency(pm/V) High requency(pm/V)
γ13
γ23
γ33
γ51
γ42
9.5
15.7
36.3
7.3
9.3
8.8
13.8
35.0
6.9
8.8
Dielectric constant eeff=13

 

Sellmeier equations of KTP Crystal
nx2=3.0065+0.03901/(λ2-0.04251)-0.01327λ2
ny2=3.0333+0.04154/(λ2-0.04547)-0.01408λ2
nz2=3.3134+0.05694/(λ2-0.05658)-0.01682λ2