KTP crystal

(Potassium Titanyl Phosphate – KTiOPO₄)

(Potassium Titanyl Phosphate – KTiOPO4) efficiency, high damage threshold and handling ease makes this one of the most widely used crystal for laser applications in the medical, industrial, defense and scientific fields.
KTP is a non-linear optical material which is commonly used for frequency doubling diode pumped solid-state lasers such as Nd:YAG and other neodymium-doped lasers. This material has a relatively high optical damage threshold (~15 J/cm²), a great optical nonlinearity and excellent theoretical thermal stability.
It is also frequently used as an optical parametric oscillator for near IR generation up to 4 µm. It is particularly suited to high power operation as an optical parametric oscillator due to its high damage threshold and large crystal aperture. The high degree of birefringent walk off between the pump signal and idler beams present in this material limit its use as an optical parametric oscillator for very low power. KTP is also used as an Electro Optic modulator, optical waveguide material, and in directional couplers.
KTP has the orthorhombic crystal structure. It is highly transparent for wavelengths between 350–2700 nm with a reduced transmission to 4500 nm. Its second harmonic generation (SHG) coefficient is about three times higher than KDP.  It has a Mohs hardness of about 5.

Features of KTP crystal:
                                      1- Large receiving angle, small off-angle

                                                  2- Wide temperature and spectral bandwidth

                                                  3- High photoelectric coefficient and low dielectric constant

                                                  4- No deliquescence, stable chemical and mechanical properties

                                                  5- High conversion efficiency

                                                  6- Large nonlinear coefficient

                                                  7- Good thermal conductivity

                       Applications:

                             Optical parametric oscillation (OPO) in near IR region up to 4 µm

                             Different frequency generation (DFG) in near IR region up to 4 µm

                             Second harmonic generation (SHG) of radiation 1.064 µm

                       Properties:

                                   Compound                              KTiOPO₄

                                   Transparency range:             0.35 – 4.5 µm

                                   Nonlinear coefficient:            d₃₁ = 2.0 pm/V; d₃₂ = 3.6 pm/V

                                   Symmetry:                              Orthorhombic, mm2 point group

                                   Cell parameters:                    a=12.818 Å, b=6.404 Å, c=10.596 Å

                                   Typical Reflection index :
                                                1064 nm                     n_x=1.7381, n_y=1.7458, n_z=1.8302
                                                532 nm                       n_x=1.7785, n_y=1.7892, n_z=1.8894

                                   Optical Damage Threshold (t=10 ns):     

1064 nm                     ~1 GW/cm²

                                   Electrooptic coefficients:      r₁₃=9.5 pm/V, r₂₃=15.7 pm/V, r₃₃=36.3 pm/V

                                   Mohs hardness:                     5

                       Parameters of optical elements:

                                               Orientation accuracy:               < 30 arc min

                                               Parallelism:                                < 30 arc sec

                                               Flatness:                                    546 nm λ/6

                                               Surface quality:                        20/10 scratch/dig