The photorefractive properties of optical planar waveguides in Fe:LiNbO3 crystals fabricated by O3+ ion implantation are investigated. Two-wave mixing experiments are carried out for both the waveguide and the bulk. The results show that the measured gain coefficients are almost identical for the waveguiding layer and the substrate. In the waveguide, the response time could be reduced by one order of magnitude, with respect to the bulk, at the same power level of the incident light. © 2008 Springer-Verlag.