Potassium titanyl phosphate (KTiOPO4, commonly abbreviated as KTP) is a nonlinear optical material widely used in a variety of photonic applications, including frequency doubling of laser sources, optical parametric oscillation, and electro-optic modulation. KTP exhibits a broad transparency range from approximately 350 nm to 4.5 μm. One of its noteworthy advantages is its high damage threshold, which makes it suitable for high-power laser applications. The crystal also exhibits good phase-matching conditions over an extensive range of wavelengths, making it a material of choice for tunable and multi-wavelength laser sources. It's commonly utilized in green laser pointers via frequency doubling of Nd:YAG or Nd:YVO4 lasers, which emit at 1064 nm. Overall, KTP's combination of optical and mechanical properties make it an important material in the field of nonlinear optics.