KTP Crystal

Featured Product from CASTECH, Inc.

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. 

CASTECH's KTP is featured by:

       •    Large nonlinear optical coefficient;
       •    Wide angular bandwidth and small walk-off angle;
       •    Broad temperature and spectral bandwidth;
       •    High electro-optic coefficient and low dielectric constant;
       •    Large figure of merit;
       •    Nonhydroscopic, chemically and mechanically stable.

CASTECH offers:
•    Strict quality control;
  •    Large crystal size up to 20x20x40mm3 and maximum length of 60mm;
    Quick delivery (2 weeks for polished only, 3 weeks for coated);
•   Unbeatable price and quantity discount;
 •   Technical support;
•    AR-coating, mounting and re-polishing service.

Table 1. Chemical and Structural Properties

 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

 Thermal Conductivity Coefficient


 Thermal Expansion Coefficient

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


Table 2. Optical and Nonlinear Optical Properties

 Transparency Range


 SHG Phase Matchable Range

 497 ~ 1800nm  (Type II)

 Thermal-optic Coefficients (/°C)


 Absorption Coefficients

<0.1%/cm at 1064nm    <1%/cm at 532nm

 For Type II SHG of a Nd:YAG laser at 1064nm

Temperature Acceptance: 24°C·cm 
Spectral Acceptance: 0.56nm·cm
Angular Acceptance: 14.2mrad·cm (φ);55.3mrad·cm (θ)
Walk-off Angle: 0.55°

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

Electro-optic Coefficients:






Low frequecy(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

Dielectric Constant εeff=13

Sellmeier Equations  

    (λ in μm)



Applications for SHG and SFG of Nd: lasers:
       KTP is the most commonly used material for frequency doubling of Nd:YAG and other Nd-doped lasers, particularly when the power density is at a low or medium level. To date, extra- and intra-cavity frequency doubled Nd:lasers using KTP have become a preferred pumping source for visible dye lasers and tunable Ti:Sapphire lasers as well as their amplifiers. They are also useful green sources for many research and industry applications.