Melting point                        1172°C

Density                                2.945 g/cm3

Transmitting range                350nm ~ 4500nm

damage threshold                 1.5-2.0MW/cm2

Flatness                               λ/8 @ 633nm

Surface quality                     10-5

Parallelism                           ≤ 10"

Perpendicularity                   ≤ 5′

KTP exhibits high optical quality, broad transparent range, relatively high effective SHG coefficient (about 3 times higher than that of KDP), rather high optical damage threshold, wide acceptance angle, small walk-off and type I and type II non-critical phase-matching (NCPM) in a wide wavelength range. 
KTP is the most commonly used material for frequency doubling of Nd:YAG lasers and other Nd-doped lasers, particularly at the low or medium power density. 


• 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 900°C

• Mechanically stable 

• Low cost compare with BBO and LBO


• 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

Frequency Conversion:

KTP was first introduced as the NLO crystal for Nd doped laser systems with high conversion efficiency. Under certain conditions, the conversion efficiency was reported to 80%, which leaves other NLO crystals far behind.

Recently, with the development of laser diodes, KTP is widely used as SHG devices in diode pumped Nd:YVO4 solid laser systems to output green laser, and also to make the laser system very compact.

KTP for OPA, OPO Applications:

In addition to its wide use as a frequency doubling device in Nd-doped laser systems for Green/Red output, KTP is also one of the most important crystals in parametric sources for tunable output from visible (600nm) to mid-IR (4500nm) due to the popularity of its pumped sources, the fundamental and second harmonic of a Nd:YAG or Nd:YLF lasers.

One of the most useful applications is the non-critical phase-matched (NCPM) KTP OPO/OPA pumped by the tunable lasers to obtain a high conversion efficiency.KTP OPO results in stable continuous outputs of femto-second pulse of 108 Hz repetition rate and milli-watt average power levels in both signal and idler outputs.

Pumped by Nd-doped lasers, KTP OPO has obtained above 66% conversion efficiency for down-conversion from 1060nm to 2120nm.

Electro-Optical modulators:

KTP crystal can be used as electro-optical modulators. For more information, please contact our sales engineers.

Basic Properties

Crystal structure


Melting point


Curie Point


Lattice parameters

a=6.404Å, b=10.615Å, c=12.814Å, Z=8

Temperature of decomposition


Transition temperature


Mohs hardness



2.945 g/cm3



Hygroscopic Susceptibility


Specific heat

0.1737 cal/g.°C

Thermal conductivity

0.13 W/cm/°C

Electrical conductivity

3.5x10-8 s/cm (c-axis, 22°C, 1KHz)

Thermal expansion coefficients

a1 = 11 x 10-6 °C-1
a2 = 9 x 10-6 °C-1
a= 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

Transmitting range

350nm ~ 4500nm

Phase Matching Range

984nm ~ 3400nm

Absorption coefficients

a < 1%/cm @1064nm and 532nm

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 Åcm

Walk-off angle

1 mrad

Optical damage threshold


Technical Parameters


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

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


λ/8 @ 633nm

Scratch/Dig code

10/5 Scratch/dig per MIL-O-13830A


better than 10 arc seconds for NKC series


5 arc minutes for NKC series

Wavefront distortion

less than λ/8 @ 633nm

Clear aperture

90% central area

Working temperature

25°C - 80°C


dn ~10-6/cm