Radiation damage and refractive index of ion-implanted LiNbO3

The formation of radiation damage in LiNbO3 crystals implanted at room temperature with N+, O+ and Ne+ ions, was analyzed by RBS, density and refractive index measurements. We have found that there are two steps in the dose dependence: 1) Formation of point defects and simple defect clusters connected with a remarkably high refractive index change in the low dose region. 2) Amorphization of the implanted surface layer in a narrow dose range around 1015 cm-2 followed by the saturation of volume expansion (ΔV(max)/V = 0.10 +- 0.02) and refractive index change (-Δn(max)0 = 0.165 +- 0.015, -Δn(max)sub(e) = 0.105 +- 0.015 at 0.6328 μm). (orig.)