Lithium niobate optical waveguides were fabricated on (110), and (100) sapphire by both diode and magnetron rf sputtering at 500-600°C in a flowing Ar/O2 atmosphere. Light coupling utilizing a rutile prism coupler was demonstrated. The propagation losses were obtained by measuring the scattered light from the surface using a fiber probe. The mode angles were also measured and used to calculate the thickness and the refractive indices of each sample. X-ray diffraction studies and the birefringence observed in the films have confirmed the crystalline nature of the films. The lowest value of attenuation of the He-Ne laser light propagating in the lithium niobate waveguide sputtered on sapphire was determined to be 1.1 ± 0.1 dB/cm. In addition, the lowest attenuation in lithium niobate thin film waveguides sputtered on SiO2/Si substrates was measured to be 2.3 dB/cm using end-fire coupling and fiber probing techniques.