Domain inversion in KTiOPO₄ using electron beam scanning

Domain inversion in c-cut KTiOPO4 was produced by scanning an electron beam on the -c face. The domain reversal occurred through the 1 mm thickness of the sample. Second-harmonic conversion efficiency of 7×10-5 was measured for a fifth-order grating by focusing the beam to a 7 μm spot in a 500-μm-long domain-inverted KTP crystal. This efficiency is close to the theoretical value of 9×10-5. The measured phase matching bandwidth was 1.9 nm, which is in agreement with the theoretical value of 1.5 nm indicating that the domain-inverted grating is reasonably uniform over its entire length.