NLO Crystals

/KTP Nonlinear crystal Potassium Titanyl Phosphate

KTP Nonlinear crystal Potassium Titanyl Phosphate

Potassium Titanyl Phosphate (KTiOPO4 or KTP) is widely used in both commercial and military lasers including laboratory and medical systems, range-finders, lidar, optical communication and industrial systems.

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    Fuzhou, China
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KTP Nonlinear crystal Potassium Titanyl Phosphate is the most commonly used material for frequency doubling of Nd-doped lasers, particularly at the low or medium power density. It is widely used for frequency mixing to generate Red/Green/Blue output, and for OPO and OPA to generate visible to mid-infrared tunable output. It is also used for many E-O devices such as Q-switches and E-O modulators.

Main applications:

1) Frequency Doubling (SHG) of Nd-doped Lasers for Green/Red Output;

2) Frequency Mixing (SFM) of Nd Laser and Diode Laser for Blue Output;

3) Parametric Sources (OPG, OPA and OPO) for 600nm - 4500nm Tunable Ouptut;

4) E-O Modulators, Optical Switches, Directional Couplers;

5) Optical Waveguides for Integrated NLO and E-O DevicesOPA and OPO.


1) Large nonlinear optical coefficient;

2) Wide angular bandwidth and small walk-off angle

3) Broad temperature and spectral bandwidth;

4) High Electro-Optics(E-O) coefficient and low dielectric constant;

5) Non-hygroscopic, chemically and mechanically stable

Optical and Nonlinear properties of KTP crystal

Transparency Range


SHG Phase Matchable Range

497 ~ 1800nm (Type II)

Therm-optic Coefficient (/, λ in μm)


Absorption Coefficients

<0.1%/cm at 1064nm <1%/cm at 532nm

Angle Acceptance

14.2mrad·cm (φ);55.3mrad·cm (θ) for Type II SHG of a Nd:YAG laser at 1064nm

Temperature Acceptance

24°C·cm for Type II SHG of a Nd:YAG laser at 1064nm

Spectral Acceptance

0.56nm·cm for Type II SHG of a Nd:YAG laser at 1064nm

Walk-off Angle

0.55° for Type II SHG of a Nd:YAG laser at 1064nm

NLO Coefficients

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

Sellmeier Equations (λ in μm)


Electro-optic Coefficients:






Low and High frequency (pm/V)

9.5 and 8.8

15.7and 13.8

36.3 and 35

7.3 and 6.9

9.3 and 8.8

Relative Dielectric Constant


Physical properties of KTP crystal

Crystal Structure

Orthorhombic, space group Pna21,point group mm2

Lattice Parameter

a=6.404Å, b=10.616Å, c=12.814A, Z=8

Melting Point

About 1172°C

Mohs Hardness



3.01 g/cm3

Refractive indices

nX = 1,7404; nY = 1,7479; nZ = 1,8296 @1064 nm

Thermal Conductivity


Thermal Expansion Coefficients

ax=11x10-6/, ay=9x10-6/, az=0.6x10-6/

HGO offers KTP specifications:

Tolerance of cutting angle


Tolerance of dimension

Dimension+0/-0.1 mmL±0.1mm


λ/10 @ 632.8nm

Wavefront distortion

λ/8@ 632.8nm

Surface quality

10/5 per MIL-O-13830A





Clear Aperture:

> 90%


< 0.1 mm @ 45°


Upon customer request


AR/HR coating upon customer’s request

Damage Threshold

750MW/CM2 at 1064nm, TEM00, 10ns, 10Hz

Quality Warranty Period

One year under proper use

Why Choose HGO ?

HGO can supply high quality potassium titanyl phosphate (KTiOPO4, KTP) nonlinear crystals. Size up to 20mm*20mm*40mm and length from 0.1mm up to 80mm.

Besides, HGO provides high grey track resistance HGTR-KTP crystals as a solution, which significantly improves the grey-track resistance and overall performance. HGTR-KTP crystals extend the use of KTP as a nonlinear medium to high-power applications.

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