On-chip Spectrometer based on Al₂O₃ Arrayed Waveguide Gratings in the UV-blue Range

Arrayed waveguides gratings (AWGs) are among the most common technologies in wavelength division multiplexing (WDM) and have promising applications in
telecommunication and sensing. These devices are typically realized in material
platforms such as silicon-on-insulator (SOI) and silicon nitride (SiN). With the emergence of material platforms that support low-loss propagation in the ultraviolet wavelength range, demonstrations of devices operating at these wavelengths are a subject of interest. Al₂O₃ is one of the materials that is studied in the context of integrated photonic circuits that target UV wavelengths. In this paper, we propose based on simulations, promising Al₂O₃-based AWGs for the development of a UV-blue (340-480 nm) spectrometer. The devices are fully etched and are designed at wavelengths of 369 and 452 nm. Here, 4- and 8-channels AWGs are proposed with corresponding wavelength channel spacing
of 2.5 and 5 nm. Insertion losses range from 3 to 6 dB. We believe that these AWGs could pave the way towards potential medical applications in UV-VIS spectroscopy, biosensing and bioimaging.