Nanolaminate structures fabricated by ALD for reducing propagation losses and enhancing the third-order optical nonlinearities

Abstract

We demonstrate a novel atomic layer deposition (ALD) process to make high quality nanocrystalline titanium dioxide (TiO2) and zinc oxide (ZnO) with intermediate Al2O3 layers to limit the crystal size. The waveguide losses of TiO2/Al2O3 nanolaminates measured using the prism coupling method for both 633 nm and 1551 nm wavelengths are as low as 0.2 ± 0.1 dB/mm with the smallest crystal size. We also show that the third-order optical nonlinearity in ZnO/Al2O3 nanolaminates can be enhanced by nanoscale engineering of the thin film structure.