Numerical analysis of a high-efficiency dual-material waveguide-grating coupler system for ultraviolet photonics

The unique capabilities of photonic integrated circuits (PICs) position them as a high-performance and scalable platform, enabling a broad spectrum of applications ranging from classical communication to pioneering quantum technologies. Despite the significant success of visible and near-infrared PICs, extending light integration into the ultraviolet-near ultraviolet (UV-NUV) wavelength range poses substantial challenges due to the technology’s relatively immature development. In this study, we introduce a novel dual-material waveguide-grating coupler system that employs aluminum oxide (Al 2 O 3 ) as the waveguide and aluminum nitride (AlN) as the grating coupler, leveraging their complementary optical properties. Given their large band gaps combined with a demonstrated low-loss propagation in Al 2 O 3 at UV wavelengths and the high refractive index of AlN, we present a pathway for significant efficiency improvements and reduced device footprint through finite-difference time-domain simulations. Notably, the monolithic integration of these materials within CMOS-compatible processes presents a viable approach to harnessing the UV-NUV regime for on-chip light routing and input/output devices.