Printable Version

KTP Crystal (KTiOPO4)

Crystals >>> Nonlinear Crystals >>>  KTP Crystal

Potassium Titanium Oxide Phosphate (KTiOPO4 ), or KTP, is an efficient nonlinear optical crystal in the visible to infrared spectral region with relatively low cost. It has large nonlinear coefficient. The effective nonlinear optical coefficient of KTP deff at 1064nm is more than 1.5 times that of BBO. It's damage threshold is near 1 GW/cm2 for 1 Hz 10 ns pulses at 1064nm. However, it is now limited to moderate to low power applications due to it's gray-tracking problem. Recently we have developed gray-tracking-improved KTP (i-KTP) which has significantly raised the gray-tracking trigger power. 


  • 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

  • High thermal conductivity (2 times that of BNN crystal )

  • Moisture free

  • Minimum mismatch gradient

  • Super-polished optical surface

  • No decomposition below 900C

  • Mechanically stable 

  • Low cost compare with BBO and LBO


  • Gray-tracking at high power limited it's application to moderate power density

Additional applications for KTP include mixed frequency, electro-optical modulation, optical parametric generation and optical waveguide.  


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

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

  • Parametric Sources (OPG, OPA and OPO) for 0.6mm-4.5mm Tunable Output

  • Electrical Optical(E-O) Modulators, Optical Switches, and Directional Couplers

  • Optical Waveguides for Integrated NLO and E-O Devices

Main Specifications  
Dimension  1x1x0.05 - 30x30x40 mm
Phase matching type Type II, θ=90; φ=phase-matching angle
Typical Coating a) S1&S2: AR @1064nm R<0.1%; AR @ 532nm, R<0.25%.

b) S1: HR @1064nm, R>99.8%; HT @808nm, T>5%
S2: AR @1064nm, R<0.1%; AR @532nm, R<0.25%

Customized coating available upon customer request.
Angle tolerance 6'
Δθ< 0.5; Δφ< 0.5
Dimension tolerance 0.02 - 0.1 mm
(W 0.1mm) x (H 0.1mm) x (L + 0.2mm/-0.1mm) for NKC series
Flatness λ/8 @ 633nm
Scratch/Dig code 10/5 Scratch/dig per MIL-O-13830A
Parallelism <10'
better than 10 arc seconds for NKC series
Perpendicularity 5'
5 arc minutes for NKC series
Wavefront distortion less than λ/8 @ 633nm
Clear aperture  90% central area
Working temperature 25C - 80C
Homogeneity dn ~10-6/cm 

To inquire or order a finished KTP crystals, please provide detailed specifications as listed in the above.  We require engineering drawing for specific orientation.  For special applications, please consult us for the designs if you are sure about the phase matching angle .

Physical and Chemical Properties
Crystal structure Orthorhombic
Point group mm2
Melting point 1172C incongruent
Lattice parameters a=6.404, b=10.615, c=12.814, Z=8
Temperature of decomposition ~1150C
Transition temperature 936C
Mohs hardness ~5
Density 2.945 g/cm3
Color colorless
Hygroscopic susceptibility no
Specific heat 0.1737 cal/g.C
Thermal conductivity 0.13 W/cm/C
Electrical conductivity 3.5x10-8 s/cm (c-axis, 22C, 1KHz)
Thermal expansion coefficients a1 = 11 x 10-6 C-1
a2 = 9 x 10-6 C-1
a3 = 0.6 x 10-6 C-1
Thermal conductivity coefficients k1 = 2.0 x 10-2 W/cm C
k2 = 3.0 x 10-2 W/cm C
k3 = 3.3 x 10-2 W/cm C
Dielectric constant eeff = 13
Optical Properties
Transmitting range 350nm ~ 4500nm
Refractive indices

Absorption coefficients a < 1%/cm @1064nm and 532nm
Therm-optic coefficients dnx/dT=1.1x10-5/C
Electro-optic coefficients
Low frequency (pm/V) High frequency 
r13 9.5 8.8
r23 15.7 13.8
r33 36.3 35.0
r51 7.3 6.9
r42 9.3 8.8
Sellmeier equations nx2=2.10468 + 0.89342λ2/(λ2-0.04438)-0.01036λ2
ny2=2.14559 + 0.87629
nz2=1.9446 + 1.3617
Nonlinear Properties
Phase matching range 497nm 3300 nm
Nonlinear coefficients
 (@ 10-64nm)
d31=2.54pm/V, d31=4.35pm/V, d31=16.9pm/V
d24=3.64pm/V, d15=1.91pm/V at 1.064 mm
Effective nonlinear optical coefficients deff(II)≈ (d24 - d15)sin2qsin2j - (d15sin2j + d24cos2j)sinq
Type II SHG of 1064nm Laser
Phase matching angle q=90, f=23.2  
Effective nonlinear optical coefficients deff 8.3 x d36(KDP)  
Angular acceptance Dθ= 75 mrad  Dφ= 18 mrad
Temperature acceptance  
Spectral acceptance 5.6 cm
Walk-off angle 1 mrad
Optical damage threshold 1.5-2.0MW/cm2



Toll Free(U.S.) 888.309.5061 Fax 650.618.2057

Copyright 2010 Red Optronics.  All Rights Reserved.