Hybrid photonic coronagraphy: integration and testing on the SEAL testbed

Photonic integrated circuits (PICs) can act as coronagraphs by routing telescope light through Mach–Zehnder interfermeter meshes whose phase shifters direct starlight away from the nulled channels. However, imperfections in the PIC limit performance. We investigate hybrid photonic coronagraphs that place a bulk-optic coronagraph upstream, suppressing most starlight before injection and substantially relaxing PIC tolerance requirements. We test this concept by integrating a NASA Ames AstroPIC device into the UCSC SEAL testbed, performing free-space injection of focal-plane light using a microlens array aligned to on-chip grating couplers . We outline the prototype’s optical, mechanical, and thermal design and report initial throughput, contrast, and stability measurements, comparing direct and hybrid injection. These results probe the feasibility of hybrid photonic coronagraphy for next-generation high-contrast imagers for both ground- and space-based telescopes.