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EO crystal
optical crystal
KTP
Potassium Titanyl Phosphate (KTiOPO4, KTP) is a high-performance frequency doubling crystal, which is widely used in commercial and scientific research, including laboratories, medical systems, range ..
Product description
Potassium Titanyl Phosphate (KTiOPO4, KTP) is a high-performance frequency doubling crystal, which is widely used in commercial and scientific research, including laboratories, medical systems, range detectors, lidars, optical communications, and industrial laser systems.
Product Introduction
Potassium Titanyl Phosphate crystals (KTiOPO4, KTP) are widely used in commercial and scientific research, including laboratory and medical laser systems, rangefinders, lidars, optical communications, and industrial laser systems.
Main Advantages
- Large nonlinear optical coefficient
- Large acceptance angle and small walk-off angle simultaneously
- Broad temperature and spectral bandwidth
- High electro-optic coefficient and low dielectric constant
- Large figure of merit
- Non-deliquescent, stable chemical and mechanical properties
What We Can Provide
- Strict quality control
- Large size, up to 20×20×40 mm3 , and the longest can reach 60 mm
- Fast delivery (The delivery time for polished wafers is 15 working days, and the delivery time for coated products is 20 working days)
- Competitive prices and volume discounts
- Technical support
- Anti-reflection (AR-coating) film deposition, holder assembly, and re-polishing and coating services
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Crystal Structure
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Orthorhombic system, space group Pna21, point group mm2
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Unit 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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Approximately 1172 ℃
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Mohs Hardness
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5 Mohs
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Density
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3.01 g/cm3
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Thermal Conductivity
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13 W/m/K
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Coefficient of Thermal Expansion
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αx = 11×10-6 /℃, αy = 9×10-6 /℃, αz = 0.6×10-6 /℃
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Transmission Range
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350-4500 nm
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SHG Phase Matching Range
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497-1800 nm (Type Ⅱ)
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Thermo-Optic Coefficient (λ unit μm)
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dnx/dT = 1.1×10-5 /℃
dny/dT = 1.3×10-5 /℃
dnz/dT = 1.6×10-5 /℃
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Absorption Coefficient
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<0.1%/cm @ 1064 nm, <1%/cm @ 532 nm
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Type II SHG of 1064 nm Nd:YAG Laser
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Temperature Bandwidth
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24 ℃·cm
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Acceptance Spectral Width
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0.56 nm·cm
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Acceptance Angle
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14.2 mrad•cm (Φ); 55.3 mrad•cm (θ)
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Walk-off Angle
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0.55°
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NLO Coefficient
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deff（Ⅱ）≈（d24 - d15）sin2Φsin2θ - （d15sin2Φ + d24cos2Φ）sinθ
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Non-zero Nonlinear Optical Coefficient
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d31 = 6.5 pm/V d24 = 7.6 pm/V
d32 = 5 pm/V d15 = 6.1 pm/V
d33 = 13.7 pm/V
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Sellmeier Equation (λ unit μm)
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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
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Electro-Optic Coefficient
r13
r23
r33
r51
r42
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Low Frequency (pm/V) High Frequency (pm/V)
9.5 8.8
15.7 13.8
36.3 35.0
7.3 6.9
9.3 8.8
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Dielectric Constant
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ɛeff = 13
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Frequency Doubling and Mixing Applications in Nd-Doped Lasers
The KTP crystal is the most commonly used material for frequency doubling of Nd:YAG and other Nd-doped lasers, especially in lasers with medium and low power densities. Up to now, Nd-doped gain lasers using KTP crystals for intracavity and extracavity frequency doubling have become common pump sources and amplifiers for visible dye lasers and tunable Ti:sapphire lasers. In many scientific research and industrial applications, such lasers are also widely used as green light sources.
- Through extracavity frequency doubling, a Nd:YAG Q-switched laser with a 900 mJ seed injection can obtain a 700 mJ green light output with a conversion efficiency of nearly 80%.
- A 15 W LD-pumped Nd:YVO4 laser with intracavity KTP crystal frequency doubling can obtain an 8 W green light output. The KTP crystal can also be used for mixing the 810 nm diode pump light and the 1064 nm Nd:YAG laser intracavity to generate blue light, as well as for intracavity frequency doubling of a 1300 nm Nd:YAG laser or Nd:YAP laser to generate red light.
Applications in Optical Parametric Amplification and Oscillation (OPA and OPO)
As shown in Figure 3 and Figure 4, due to the second harmonic effect and optical parametric amplification performance of the KTP crystal, it plays a core role in the output wavelength adjustment (from 600 nm visible light to 4500 nm mid-infrared) of tunable Nd ion lasers.
Typically, the OPO of the KTP crystal can achieve a stable and continuous pulse output (signal light and idler light) at the fs level with a repetition frequency of up to 108 Hz and a small average power level. Using KTP for optical parametric amplification, the 1064 nm pump light of the Nd:YAG laser can be converted into 2120 nm light, with a conversion efficiency of over 66%.
Typically, the OPO of the KTP crystal can achieve a stable and continuous pulse output (signal light and idler light) at the fs level with a repetition frequency of up to 108 Hz and a small average power level. Using KTP for optical parametric amplification, the 1064 nm pump light of the Nd:YAG laser can be converted into 2120 nm light, with a conversion efficiency of over 66%.
The KTP crystal also has a new application, that is, the OPO/OPA of non-critical phase-matched KTP crystals. As shown in Figure 5, the pump wavelength range is from 700 nm to 1000 nm, and the output wavelengths are from 1040 nm to 1450 nm (signal wave) and from 2150 nm to 3200 nm (idler wave), with a conversion efficiency of >45% for high-quality narrow-bandwidth beams.
In addition to its nonlinear properties, KTP is also widely used in the E-O field due to its insulating properties, especially as a tunable E-O device. Table 3 shows the comparison between KTP and other E-O module materials:
Applications in Electro-Optic Devices
In addition to its nonlinear properties, the KTP crystal also has excellent electro-optic effects and dielectric properties comparable to those of the LiNbO3 crystal, and is widely used in electro-optic devices. Table 1 shows the comparison between the KTP crystal and other commonly used electro-optic modulation materials:
Applications in Electro-Optic Devices
In addition to its nonlinear properties, the KTP crystal also has excellent electro-optic effects and dielectric properties comparable to those of the LiNbO3 crystal, and is widely used in electro-optic devices. Table 1 shows the comparison between the KTP crystal and other commonly used electro-optic modulation materials:
| Material | ε | N | Phase | Amplitude | ||||
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R
（pm/V）
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K
（10-6/℃）
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N7r2/ε
（pm/V)2
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r
（pm/V）
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K
（10-6/℃）
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n7r2/ε
（pm/V)2
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| KTP | 15.42 | 1.80 | 35.0 | 31 | 6130 | 27.0 | 11.7 | 3650 |
| LiNbO3 | 27.90 | 2.20 | 8.8 | 82 | 7410 | 20.1 | 42.0 | 3500 |
| KD*P | 48.00 | 1.47 | 24.0 | 9 | 178 | 24.0 | 8.0 | 178 |
| LiIO3 | 5.90 | 1.74 | 6.4 | 24 | 335 | 1.2 | 15.0 | 124 |
From the comprehensive view of Table 1, the KTP crystal, with its characteristics such as high damage threshold, wide optical frequency width (>15 GHz), stable thermal and mechanical properties, and low loss, is expected to replace the LiNbO3 crystal in the mass application field of electro-optic modulators.
Applications in Optical Waveguides
By performing ion exchange treatment on the KTP substrate, low-loss optical waveguide devices can be obtained. This technology has enabled KTP to have more applications in the field of integrated optics; Table 4 shows the comparison between KTP and other optical waveguide materials. Recently, a type II SHG conversion efficiency of 20% /W/cm2 has been achieved through balanced phase matching. In addition, segmented KTP waveguides have been applied to type I quasi-phase-matched SHG of tunable Ti:Sapphire lasers in the 760-960 mm band, as well as direct frequency doubling of diode lasers with an output wavelength of 400-430 nm.
| Material | r（pm/V） | n | εeff (ε11ε33)1/2 | n3r/εeff (pm/V) |
| KTP | 35 | 1.86 | 13 | 17.30 |
| LiNbO3 | 29 | 2.20 | 37 | 8.30 |
| KNbO3 | 25 | 2.17 | 30 | 9.20 |
| BNN | 56 | 2.22 | 86 | 7.10 |
| BN | 56-1340 | 2.22 | 119-3400 | 5.1-0.14 |
| GaAs | 1.2 | 3.60 | 14 | 4.00 |
| BaTiO3 | 28 | 2.36 | 373 | 1.00 |
Specifications of KTP Crystals
| Size Tolerance |
(W±0.1 mm)×(H±0.1 mm)×(L+0.5/-0.1 mm) (L≥2.5 mm)
(W±0.1 mm)×(H±0.1 mm)×(L+0.1/-0.1 mm) (L＜2.5 mm)
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| Effective Aperture | 90% of the central area |
| Internal Quality | No visible scattering path or center detected by 50 mW green light |
| Surface Finish | 10/5, referring to MIL-PRF-13830B standard |
| Flatness | ≦λ/8 @ 633 nm |
| Transmission Wavefront Distortion | ≦λ/8 @ 633 nm |
| Parallelism | 20″ |
| Perpendicularity | ≦15′ |
| Angle Tolerance | ≦0.25° |
| Chamfer | ≦0.2 mm×45° |
| Edge Chipping | ≦0.1 mm |
| Damage Threshold |
>1 GW/cm2 @ 1064 nm, 10 ns, 10 Hz (Anti-reflection Coating)
>0.3 GW/cm2 @ 532 nm, 10 ns, 10 Hz (Anti-reflection Coating)
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| Quality Assurance Period | One year (under normal use) |
We Can Provide the Following Film Systems
- Low-reflectivity dual-wavelength anti-reflection film AR-1064/532nm for the frequency doubling of 1064 nm, with R＜0.2% @ 1064 nm and R＜0.5% @ 532 nm.
- High-reflection film HR-1064 nm&HT-532 nm, with R＞99.8% @ 1064 nm and T＞90% @ 532 nm.
- Broadband anti-reflection (BBAR-coating) or protective (P-coating) films for the OPO of KTP crystals.
- High laser damage resistance threshold (>300 MW/cm2 @ 1064/532 nm).
- Long service life.
- Customized film system services are available.
