Total Ionizing Dose Effects on Silicon Nitride Photonic Integrated Microring Resonators and Mach–Zehnder Interferometers

Silicon nitride (SiN) photonic integrated circuits (PICs) are a promising technology for satellite applications. In particular, they could be employed in satellite payloads for optical communications, allowing for the integration of optical functionalities on a chip, thus reducing the payload footprint. The research on the space environmental effects of this technology platform is still novel. Here, an experimental characterization of ionizing dose effects on integrated microring resonators (MRRs) and Mach-Zehnder interferometers (MZIs) is presented. Hundreds of devices with different waveguide widths were fabricated and characterized before and after irradiation, thanks to a highly automated setup. The impact of radiation in terms of additional losses, change in effective index, and change in the group index was evaluated. Furthermore, the long-term evolution of the effects after irradiation was also monitored. A change in the effective index as high as 2 × 10−3 and an increase in losses as large as 1 dB/cm were measured. The measured impact on the effective index and the group index, although relatively small, would be detrimental to applications such as wavelength filtering and/or (de)multiplexing and will need to be taken into account when designing devices for optical satellite communications.