KTP

KTP is an acronym that can refer to several different concepts. Two of the most common are Kartu Tanda Penduduk, the Indonesian national identity card, and potassium titanyl phosphate, a nonlinear optical crystal used in photonics.

In Indonesia, the Kartu Tanda Penduduk (KTP) is issued by civil registration authorities to residents as a formal identity document. The program evolved into an electronic version known as e-KTP or KTP-el, which stores biometric data on a chip and is used to verify identity in administrative and financial transactions. The system aims to streamline identification and reduce impersonation, though it has also been the subject of privacy and security concerns and ongoing updates.

Potassium titanyl phosphate (KTP) is a crystalline material with the chemical formula KTiOPO4. It is valued in nonlinear optics for its wide transparency range, relatively high nonlinear coefficients, and suitability for phase matching. KTP and periodically poled variants (PPKTP) are widely used for frequency conversion, such as second-harmonic generation, as well as for electro-optic modulation of lasers and other photonic applications.

Other uses of the acronym exist in various fields, but the two meanings above are the most widely encountered. The term KTP should be interpreted from context to determine whether it refers to the Indonesian identity document or the optical crystal.