An Optical Waveguide Formed by Aluminum Nitride thin film on Sapphire

We have investigated an optical waveguide formed by aluminum nitride (AlN) thin film on sapphire. A good quality AlN thin film on sapphire substrate was prepared by metal organic chemical vapor deposition (MOCVD) in this laboratory. A rutile prism coupler was employed to display the waveguide modes (N-lines) with wavelengths of 632.8, 532.1, 514.5 and 488.0 nm. The refractive index and thickness of the waveguide material is obtained by prism-coupler measurement. The dispersion curve of the AlN film is given and the dispersion equation is derived. The attenuation in the waveguide is evaluated by scattering loss measurements using a fiber probe. The attenuation coefficient alpha (α) is 1.5- 2.1 cm −1 depending on the sample and the different modes of waveguide. The accuracy of the measurement is discussed.