KTP Crystal

• Large nonlinear optical coefficient

• Wide angular bandwidth and small walk-off angle

• Broad temperature and spectral bandwidth

• High electro-optic coefficient and low dielectric constant

• Large figure of merit

• Nonhydroscopic, chemically and mechanically stable

• High thermal conductivity

• Moisture free

• Minimum mismatch gradient


KTP (Potassium Titanyl Phosphate, KTiOPO4) is a nonlinear optical material generally used for doubling of solid-state lasers, such as Nd:YAG. The crystal has a relatively high optical damage threshold, a large optical nonlinearity of second-harmonic generation (SHG) and excellent thermal stability. Its SHG coefficient is approximately three times higher than KDP, and it is often used as an optical parametric oscillator (OPO) for near IR generation up to 3 µm.

Chemical and Physical Properties

Crystal Structure Orthorhombic, point group mm2
Lattice Parameters a=6.404Å, b=10.616Å, c=12.814Å; Z=8
Density 3.02 g/cm3
Mohs Hardness ~ 5
Melting Point 1172°C (Incongruent)
Curie Point 936°C
Specific Heat 0.1643 cal/goC (25°C)
Dielectric Constant eeff = 13
Absorption Coefficient < 0.1%/cm@1.064μm and < 1%/cm@0.532μm
Thermal Conductivity 13 W/m/°C
Electrical Conductivity 1.22×10-6s/cm (c-axis, 22oC, 2KHz)
Hygroscopic Susceptibility no
Dimension Tolerance (W±0.1mm) x (H±0.1mm) x (L+0.2/-0.1 mm) (L≥2mm)
(W±0.1mm) x (H±0.1mm) x (L±0.1 mm) (L<2mm)
Absorption <0.01%@1064nm, <1%@532nm
Cutting Angle Tolerance Dq< ±0.2°, Df< ±0.2°
Wavefront Distortion <λ/8 @632.8 nm
Chamfer ≤ 0.15 mm x 45°
Perpendicularity < 5 arc minutes
Parallelism < 20 arc seconds
Flatness <λ/10 @633 nm
Scratch/Dig 10/5 per MIL-PRF-13830B
Clear Aperture > Central 90%
Antireflection Coating R < 0.2% @1064nm, R < 0.5% @532nm