Polarization reversal and domain grating in flux-grown KTiOPO4 crystals with variable potassium stoichiometry

A significant decrease is observed in the dielectric dispersion, conductivity, coercive and internal fields of KTiOPO4 crystals grown with relatively high potassium concentration in the flux. A periodic domain structure with a period of 24.7 μm was fabricated on a 10 mm long crystal by electric field poling. Whereas standard flux-grown KTiOPO4 crystals can be periodically poled only at low temperatures (near 170 K), the periodic poling in this case was successfully performed near room temperature at a much lower electric field. Quasiphase-matched frequency doubling of 1550 nm radiation was achieved with the poled crystal.