Periodically poled KTiOPO/sub 4/

Summary form only given. Periodically poled crystals are a relatively new class of materials artificially made for quasi-phasematched (QPM) nonlinear optical frequency conversion. Crystals from the KTiOPO/sub 4/ (KTP) family are particularly attractive for periodic poling as they have low coercive fields (approximately 10 times lower than LiNbO/sub 3/) and a quasi-one dimensional crystal structure which together makes it possible to fabricate fine pitch gratings in relatively thick crystals. These crystals are also known from conventional birefringent phasematching to have high laser damage and photorefractive damage threshold and wide acceptance bandwidth. KTP is the most easily grown crystals in the family and it has become the primary nonlinear element choice for green frequency doubled lasers and for OPOs.