ZnO-based active integrated photonic devices for the ultraviolet band

Ultraviolet (UV) communication offers significant advantages for military and industrial applications, such as non-line-of-sight transmission, enhanced security, and robust anti-jamming capabilities. However, the development of integrated UV photonics significantly lags behind visible and near-infrared systems, primarily due to a shortage of suitable active materials and a lack of effective on-chip integration strategies. This work addresses this critical gap by demonstrating a UV integrated photonic platform based on zinc oxide (ZnO) with a pistol-shaped microstructure. We successfully synthesized waveguide-connected microdisks that monolithically integrate a gain medium, a high-Q whispering-gallery-mode laser cavity (Q ≈ 1300), and a waveguide. The structure enables highly directional and on-chip transmission of UV laser emission. Furthermore, the coupled microdisk-waveguide system achieved a guided-propagation efficiency of 22.9%. The combination of spectroscopic measurements and finite-difference time-domain simulations confirms the lasing mechanism and efficient signal routing. This study not only establishes ZnO as a formidable material for active UV photonics but also provides a novel and robust architecture for realizing complex on-chip functionalities.