Potassium titanyl phosphate (KTP) crystal (KTiOPO₄) is an excellent nonlinear crystal. The following are its relevant parameters: 

Structural Parameters

Crystal Structure: It belongs to the frequency - doubling photoelectric crystals among inorganic crystals, with an orthorhombic crystal system and the space group Pna2(1). In the crystal, titanium atoms, oxygen atoms, and phosphorus atoms form a grid structure, and potassium ions are distributed within it, having non - central symmetry.

Unit Cell Parameters: a = 12.818 Å, b = 6.404 Å, c = 10.596 Å.

Symmetry Degree: Orthorhombic system, mm2 point group.

Optical Parameters

Transmittance Range: 0.35 - 4.5µm.

Non - linear Coefficients: d₃₁ = 2.0 pm/V; d₃₂ = 3.6 pm/V.

Typical Reflection Coefficients: At 1064nm, nx = 1.7381, ny = 1.7458, nz = 1.8302; at 532nm, nx = 1.7785, ny = 1.7892, nz = 1.8894.

Wavefront Distortion: λ/8 @ 633nm.

Flatness: λ/8 @ 633nm.

Coating: AR/AR @ 1064 + 2128nm (R < 0.2%).

Optical Damage Threshold: 450 MW/cm² at 1064nm (t = 10ns, 10Hz).

Other Parameters

Wavelength Conversion: 1064nm (o) --> 2128nm (o) + 2128nm (e).

Parallelism: < 20 arc sec.

Surface Finish: 20 - 10.

Orientation: < 12 arc minutes.

Crystal Size: Commonly 6x6x20mm³.