Low-loss epitaxial ZnO optical waveguides on sapphire by rf magnetron sputtering

Optical waveguide loss of about 0.55 dB cm−1 has been measured on epitaxial ZnO films on sapphire by magnetron sputtering. Measurements were also made of the refractive index of those films. The experimental results are compared with theory when TE and TM guided waves propagate in the plane at an arbitrary angle with respect to the c axis where the c axis is lying in the plane of the film. Surface acoustic wave (SAW) properties were also measured for SAW propagating along the c axis of ZnO film on the (011̄2)-oriented Al2O3 substrate.