Abstract: A method of growing a single crystal of KTiOPO.sub.4 which is a nonlinear optical material is disclosed. Growth of the single crystal of KTiOPO.sub.4 is carried out by melting a KTiOPO.sub.4 material with a flux to produce a melt, then contacting a seed crystal to the melt, and by slowly cooling at a saturation temperature or below. At this time, molar fractions of K.sub.2 O, P.sub.2 O.sub.5 and TiO.sub.2 contained in the melt fall within a region surrounded by six point in a K.sub.2 O-P.sub.2 O.sub.5 -TiO.sub.2 ternary phase diagram of A (K.sub.2 O:0.4150, P.sub.2 O.sub.5 :0.3906, TiO.sub.2 : 0.1944), B (K.sub.2 O:0.3750, P.sub.2 O.sub.5 : 0.3565, TiO.sub.2 : 0.2685), C (K.sub.2 O: 0.3750, P.sub.2 O.sub.5 : 0.3438, TiO.sub.2 : 0.2813), D (K.sub.2 O: 0.3850, P.sub.2 O.sub.5 : 0.3260, TiO.sub.2 : 0.2890), E (K.sub.2 O: 0.4000, P.sub.2 O.sub.5 : 0.3344, TiO.sub.2 : 0.2656), and F (K.sub.2 O: 0.4158, P.sub.2 O.sub.5 : 0.3744, TiO.sub.2 : 0.2098). In addition, K.sub.15 P.sub.13 O.sub.

Abstract: A flux process is disclosed for producing a single orthorhombic crystal of Cs.sub.1-x M.sub.x TiOAsO.sub.4 (where M is Na, K, Rb, and/or Tl and x is from 0 to 0.4) wherein the dimension of the crystal along each axis is at least about 2 mm, and wherein the product at the dimensions along the three axes is at least about 15 mm.sup.3. The process involves preparing a homogeneous melt containing the components for forming said crystal and a flux comprising oxides of Cs and As at a temperature no higher than the decomposition temperature of said orthorhombic crystal, the mole fraction of M relative to the total Cs+M in the melt being within the range of from 0 to about 0.2; introducing a seed crystal for said single crystal in the melt; activating the controlled crystallization on the seed crystal; and continuing the crystallization until formation of the single crystal is completed. Single crystals of Cs.sub.1-x M.sub.x TiOAsO.sub.4 (including crystals at least about 5 mm.times.5 mm 5 mm) are also disclosed.

Abstract: A method is provided for producing a KTiOPO.sub.4 which is grown at a temperature higher than its Curie temperature using a TSSG method. The grown KTiOPO.sub.4 single crystal is maintained in contact with a melt while the crystal is maintained at a temperature higher than the Curie temperature. A d.c. current is applied in this state across a seed crystal and the melt, while the single crystal is cooled to a temperature lower than the Curie temperature. The value of current density D, defined by the formula D=Ip/(a+b), where Ip is the impressed current and a, b are crystal sizes along a and b axes, respectively, is selected to be 0.01 mA/cm.sup.2 .ltoreq.D.ltoreq.1.0 mA/cm.sup.2. In this manner, the produced KTiOPO.sub.4 is processed into a single domain crystal.