Low temperature periodic electrical poling of flux-grown KTiOPO4 and isomorphic crystals

Studies of dielectric spectroscopy, de conductivity, and polarization switc hing allowed the observation of phase transition from the superionic to the insulating state in flux-grown KTiOPO4 (KTP) crystals at low temperature w here the high mobility of potassium ions is suppressed. A low temperature m ethod of fabrication of engineered periodic domain structures in superionic KTP and isomorphic crystals is proposed, It enabled us to tailor homogeneo us domain gratings with various periods in the range 4-39 mu m for quasipha se-matched nonlinear optical converters in KTP plates over whole area of 30 x30 mm(2). (C) 1998 American Institute Of Physics. [S0003-6951(98)03751-6].