TiO₂ channel waveguides with 0.5 dB/cm propagation losses: (Student paper)

Scattering represents a major contribution to the optical propagation losses of channel waveguides. By optimization of the reactive sputtering deposition process, volume scattering can be minimized. In this work, we focus on the reduction of surface scattering by applying a chemical mechanical polishing step following reactive sputter deposition of TiO2 layers. Propagation losses below 0.1 dB/cm at 980 nm of wavelength were experimentally characterized for TiO2 slabs on oxidized silicon wafers. The propagation loss increases to 0.5 dB/cm at 1550 nm of wavelength for fully etched channel waveguides. Such low propagation loss paves the way for the utilization of TiO2 in advanced integrated photonics circuits.