Er-doped KTiOPO4 films on different substrates were made by pulsed-laser deposition. Substrates included Al2O3, MgO, and KTiOPO4. Both KTiOPO4 and erbium were used as targets. The composition of the Er-doped KTiOPO4 films on the different substrates was analyzed by Rutherford backscattering with 2.1 MeV He2+. The results show that there is deficiency of K and P in the deposited KTiOPO4 film on the different substrates. The prism coupling method was used to determine the relative intensity of scattered light versus the effective refractive index. The measurement indicates that there are waveguide structures in all cases.