Sputtered aluminum nitride waveguides for the telecommunication spectrum with less than 0.16 dB/cm propagation loss

We report the fabrication and characterization of photonic waveguides from sputtered aluminum nitride (AlN). The AlN films were deposited on 6” silicon substrates with a 3 µm buried silicon oxide layer using reactive DC magnetron sputtering at a temperature of 700°C. The resulting uncladded polycrystalline waveguides exhibit propagation losses of 0.137 ± 0.005 dB/cm at wavelengths of 1310 nm and 0.154 ± 0.008 dB/cm at a wavelength of 1550 nm in the TE polarization. These results are the best reported for sputtered AlN waveguides in the C-band and the first report in the O-band. These performances are comparable to those of the best-reported AlN waveguides, which are epitaxially grown by metal-organic chemical vapor deposition (MOCVD) on sapphire substrates. Our findings highlight the potential of sputtered AlN for photonic platforms working in the telecom spectrum.