frequency generation. The interactions in PPKTP are based upon quasi-phase-matching, achieved by periodic poling of the crystal, whereby a structure of regularly spaced ferroelectric domains with alternating orientations are created in the material. PPKTP is commonly used for Type 1 & 2 frequency conversions for pump wavelengths of 730–3500 nm. Other materials used for periodic poling are wide band gap inorganic crystals like lithium niobate (resulting in periodically poled lithium niobate, PPLN), lithium tantalate, and some organic materials. See also Other materials used for laser frequency doubling are Lithium triborate (LBO), used for high output power green or blue DPSS lasers Beta barium borate (BBO), used for high output power DPSS blue lasers References External links AdvR – Periodically poled potassium titanyl phosphate & KTP waveguides Potassium titanyl phosphate Phosphates Potassium compounds Titanium(IV) compounds Nonlinear optical materials Ferroelectric materials Crystals Second-harmonic generation