KTP Crystals
What Are KTP Crystals?
Fig 1. KTP single crystals grown by TSSG method. [1]
Potassium Titanyl Phosphate (KTP, KTiOPO4) is a widely used nonlinear optical crystal prized for efficient second-harmonic generation (SHG), sum-/difference-frequency generation, optical parametric devices, and electro-optic applications. KTP offers a favorable combination of strong second-order nonlinearity, low absorption across the visible to near-IR, good thermal stability, and relatively high damage threshold when properly coated and handled. It is commonly used to frequency-double 1064 nm Nd:YAG/Yb lasers to 532 nm, and in many compact, high-power, and cw laser systems.
At Alfa Chemistry, professional-grade KTP single crystals are engineered for reliable frequency conversion, electro-optic modulation, and high-performance laser systems. Our KTP products combine excellent nonlinear efficiency, broad transparency, and stable thermal and mechanical properties — ideal for both laboratory research and OEM laser applications.
Features
- Large Nonlinear Coefficients: d24 = 7.6 pm/V, d32 = 5 pm/V, d33 = 13.7 pm/V (@1064 nm) enabling highly efficient frequency conversion.
- High Damage Threshold: >500 MW/cm2 (@1064 nm, 10 ns) for reliable high-power operation.
- Wide Transparency Range: 350 nm - 4500 nm, covering UV to mid-infrared spectral regions.
- Excellent Thermal Stability: Low thermal expansion and high thermal shock resistance.
- Non-hygroscopic Nature: Non-hygroscopic, non-deliquescent, maintains performance in various environmental conditions without degradation.
- Good Mechanical Properties: Hardness of 5.5 Mohs for durability and ease of processing.
- High Optical Quality: Excellent homogeneity with minimal wavefront distortion.
- High SHG efficiency: SHG efficiency at 1064nm reaches approximately 80%.
Specifications Product Options Applications
| Product Name | KTP Crystals |
| Catalog No. | OPTIX-0010 |
| Chemical Formula | KTiOPO4 |
| Crystal Structure | Orthorhombic, Space group Pna21, Point group mm2 |
| Lattice Parameters | a=6.404Å, b=10.616Å, c=12.814Å, Z=8 |
| Density | 3.01 g/cm3 |
| Mohs Hardness | 5 Mohs |
| Melting Point | ~ 1172 ℃ |
| Transmission Wavefront Distortion | ≤ λ/8 @633 nm |
| Angle Tolerance | ≤ 0.25 ° |
| Chamfer | ≤ 0.2 mm × 45 ° |
| Parallelism | 20 arc sec |
| Perpendicularity | < 15 arc min |
| Surface Quality (Scratch/Dig) | 10/5 to MIL-PRF-13830B |
| Flatness | ≤ λ/8 @633 nm |
| Hygroscopicity | No |
| Clear Aperture | 90% of central area |
| Coatings | AR-coatings |
| Quality Warranty Period | One year under proper use |
| Nonlinear Optical Properties |
| NLO Coefficient | deff(II)≈(d24- d15)sin2φsin2θ- (d15sin2φ+ d24cos2φ)sinθ |
| Non-vanished NLO Susceptibilities | d31 = 6.5 pm/V, d24 = 7.6 pm/V
d32 = 5 pm/V, d15 = 6.1 pm/V
d33 = 13.7 pm/V |
| SHG Phase Matchable Range | 497-1800 nm (Type Ⅱ) |
| Damage Threshold | ＞0.5 GW/cm2 @1064 nm, TEM00, 10 ns, 10 Hz (AR-coated)
＞0.3 GW/cm2 @532 nm, TEM00, 10 ns, 10 Hz (AR-coated) |
| Linear Optical Properties |
| Transparency Range | 350-4500 nm |
| Absorption Coefficients | <0.1% /cm at 1064 nm, <1% /cm at 532 nm |
| Refractive Index | nx=1.7377, ny=1.7453, nz=1.8297 @1064nm
nx=1.7780, ny=1.7886, nz=1.8887 @532nm |
| Sellmeier Equations (λ in μm) | nx2 = 3.0065 + 0.03901 / (λ2 - 0.04251) - 0.01327 λ2
ny2 = 3.0333 + 0.04154 / (λ2 - 0.04547) - 0.01408 λ2
nz2 = 3.3134 + 0.05694 / (λ2 - 0.05658) - 0.01682 λ2 |
| For Type Ⅱ SHG of a Nd:YAG laser @ 1064 nm | Temperature Acceptance: 24 ℃·cm
Spectral Acceptance: 0.56 nm·cm
Angular Acceptance: 14.2 mrad·cm (Φ); 55.3mrad·cm (θ)
Walk-off Angle: 0.55 ° |
| Thermal and Electrical Properties |
| Thermal Expansion Coefficients | ax=11×10-6/℃, ay=9×10-6/℃, az=0.6×10-6/℃ |
| Thermal Conductivity | 13W/m/K |
| Dielectric Constant | ɛeff = 13 |
| Electro-Optic Coefficients | Low frequency; High frequency
r13 = 9.5 pm/V; 8.8 pm/V
r23 = 15.7 pm/V; 13.8 pm/V
r33 = 36.3 pm/V; 35.0 pm/V
r51 = 7.3 pm/V; 6.9 pm/V
r42 = 9.3 pm/V; 8.8 pm/V |
| Thermo-Optical Coefficient | dnx/dT = 1.1×10-5 /℃
dny/dT = 1.3×10-5 /℃
dnz/dT = 1.6×10-5 /℃ |
Note: The data provided is for reference purposes. We recommend consulting with our technical team to verify suitability for your application.
KTP Crystal Product Options
- Standard KTP Crystals: Various sizes and orientations available. Crystal sizes up to 20 × 20 × 40 mm3, with a maximum length of 60 mm.
- Periodically Poled KTP (PPKTP): Custom poling periods for specific wavelength requirements.
- Orientation & Phase-Matching Cuts: X-cut, Y-cut, Z-cut, Type-I/Type-II phase-match angles, non-critical and temperature-tuned cuts.
- Coatings: Single/dual wavelength AR, broadband AR, high-power coatings, dielectric stacks optimized for pump and SH wavelengths.
- Surface Finish: Standard optical polish, superpolish (low scatter) for high-finesse cavities.
- Dimensional Tolerances: Custom thickness, tight angle tolerances, high flatness for resonators.
- Waveguide & Bonded Devices: Channel waveguide blanks or fabricated waveguide options (consult for specs).
- Quality Grades: Research grade, production/OEM grade, and high-damage-threshold grade with certified test reports.
- Second-harmonic generation (SHG) — especially 1064 nm → 532 nm conversion of Nd:YAG lasers.
- Sum-frequency / difference-frequency generation and optical parametric oscillators (OPO/OPA).
- Electro-optic modulators and Q-switches (in certain designs).
- Frequency conversion for green lasers, visible light generation, and tunable IR sources.
- Scientific instrumentation, medical lasers, lidar, and industrial laser systems.
- Compact and diode-pumped solid-state laser modules requiring robust nonlinear crystals.
Why Choose Our KTP Crystals?
- Decades of Crystal Growing & Optics Experience: Proven growth methods and process control for consistent, high-quality KTP.
- Rigorous Quality Control: Interferometry, spectrophotometry, inclusion/scatter inspection, and optional laser-damage testing with delivered reports.
- Custom Engineering Support: Our applications team helps select the optimal cut, coating, and mounting for your wavelength, pulse regime (CW/ns/ps/fs) and power level.
- Flexible Production & Fast Prototyping: From single research samples to volume OEM supply with consistent specifications.
- Comprehensive Documentation & Compliance: ISO-grade procedures, batch traceability, and export paperwork for global customers.
Reference
- Roth, M., et al. Journal of crystal growth 312.8 (2010): 1059-1064.
