Abstract
The release on the investigation between the domain size and the energy band gap in KTiOPO4 single crystals for the different light polarization directions is presented. There was found a complex relationship between the values of the band gap Eg , defectiveness, and nonlinear optical constants rij that points to the effect of the domain macrofields. The step-like temperature dependences of Eg and rij obtained reveal the possibility of arising the phase transitions induced by the macroscopic inhomogeneous domain field there.