KTP / GTR-KTP Crystal

Short Description:

KTP (KTiOPO4 ) is one of the most commonly used nonlinear optical materials. For example, it’s regularly used for frequency doubling of Nd:YAG lasers and other Nd-doped lasers, particularly at low or medium-power density. KTP is also widely used as OPO, EOM, optical wave-guide material, and in directional couplers.

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KTP (KTiOPO4 ) is one of the most commonly used nonlinear optical materials. For example, it’s regularly used for frequency doubling of Nd:YAG lasers and other Nd-doped lasers, particularly at low or medium-power density. KTP is also widely used as OPO, EOM, optical wave-guide material, and in directional couplers.

KTP exhibits a high optical quality, broad transparency range, wide acceptance angle, small walk-off angle, and type I and II non-critical phase-matching (NCPM) in a wide wavelength range. KTP also has relatively high effective SHG coefficient (about 3 times higher than that of KDP) and fairly high optical damage threshold (>500 MW/cm²).

Regular flux-grown KTP crystals suffer from blackening and efficiency breakdown ("grey-track") when used during SHG process of 1064 nm at high average power levels and repetition rates above 1 kHz. For high average-power applications, WISOPTIC offer high grey track resistance (HGTR) KTP crystals grown by hydrothermal method. Such crystals have a lower initial IR absorption and are less affected by green light than regular KTP, thus avoid the problems of harmonic power instabilities, efficiency drops, crystal blackening, and beam distortion.

As one of the major KTP source suppliers in the whole international market, WISOPTIC has high capability of material selection, processing (polishing, coating), mass production, fast delivery and long guarantee period of quality KTP. It is also worth to mention that our price is quite reasonable.

Contact us for the best solution for your application of KTP crystals.


DimensionsAs large as 10×10×15mm

Extinction Ratio>25dB

Optical Transparency Range500~2500nm

Laser-induced Damage Threshold>600MW/cm2 @1064nm,10ns,10Hz, AR coated

Insertion Loss<1.0% @1064nm

Operation Temperature-40~+65 (as high as +80)

Frequency Rangeas high as 4MHz


WISOPTIC Advantages - KTP

• High homogeneity

• Excellent internal quality

• Top quality of surface polishing

• Large block for various size (20x20x40mm3, max length 60mm)

• Large nonlinear coefficient, high conversion efficiency

• Low insertion losses

• Very competitive price

• Mass production, quick delivery

WISOPTIC Standard Specifications* - KTP

Dimension Tolerance ± 0.1 mm
Angle Tolerance < ± 0.25°
Flatness < λ/8 @ 632.8 nm
Surface Quality < 10/5 [S/D]
Parallelism < 20”
Perpendicularity ≤ 5'
Chamfer ≤ 0.2 mm @ 45°
Transmitted Wavefront Distortion < λ/8 @ 632.8 nm
Clear Aperture > 90% central area
Coating AR coating: R<0.2% @ 1064nm, R<0.5% @ 532nm
[or HR coating, PR coating, upon request ]
Laser Damage Threshold 500 MW/cm2 for 1064nm, 10ns, 10Hz (AR-coated)
* Products with special requirement upon request.

Main Features - KTP

• Efficient frequency conversion (1064nm SHG conversion efficiency is about 80%)

• Large nonlinear optical coefficients (15 times that of KDP)

• Wide angular bandwidth and small walk-off angle

• Broad temperature and spectral bandwidth

• Moisture free, no decomposition below 900°C, mechanically stable

• Low cost compare with BBO and LBO

• Gray-tracking at high power (regular KTP)

Primary Applications - KTP

• Frequency doubling (SHG) of Nd-doped lasers (particularly at low or medium-power density) for green/red light generation

• Frequency mixing (SFM) of Nd lasers and diode lasers for blue light generation

• Optical parametric sources (OPG, OPA, OPO) for 0.6-4.5µm tunable output

• E-O modulators, optical switches, directional couplers

• Optical waveguide for integrated NLO and E-O devices

Physical Properties - KTP

Chemical formula KTiOPO4
Crystal structure Orthorhombic
Point group mm2
Space group Pna21
Lattice constants a=12.814 Å, b=6.404 Å, c=10.616 Å
Density 3.02 g/cm3
Melting point 1149 °C
Curie temperature 939 °C
Mohs hardness 5
Thermal expansion coefficients ax=11×10-6/K, ay=9×10-6/K, az=0.6×10-6/K
Hygroscopicity non-hygroscopic

Optical Properties - KTP

Transparency region
  (at “0” transmittance level)
350-4500 nm 
Refractive indices   nx ny nz
1064 nm 1.7386 1.7473 1.8282
532 nm 1.7780 1.7875 1.8875
Linear absorption coefficients
(@ 1064 nm)
α < 0.01 / cm

NLO coefficients (@1064nm)

d31=1.4 pm/V, d32=2.65 pm/V, d33=10.7 pm/V

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
r42 9.3 pm/V 8.8 pm/V
r51 7.3 pm/V 6.9 pm/V
Phase matching range for: 
Type 2 SHG in x-y plane  0.99÷1.08 μm
Type 2 SHG in x-z plane 1.1÷3.4 μm
Type 2, SHG@1064 nm, cut angle θ=90°, φ=23.5°
Walk-off angle 4 mrad
Angular acceptances Δθ=55 mrad·cm, Δφ=10 mrad·cm
Thermal acceptance ΔT=22 K·cm
Spectral acceptance Δν=0.56 nm·cm
SHG conversion efficiency 60~77%

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