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 |
