AstroPIC III: advancing the near-infrared photonic integrated coronagraph for the Habitable Worlds Observatory

Abstract

AstroPIC is a photonic integrated coronagraph concept for the Habitable Worlds Observatory (HWO) that uses a programmable Mach-Zehnder interferometer mesh to perform coronagraphic mode-sorting of starlight while preserving off-axis exoplanet light. This paper presents a Gen-2 technology update and modeling study. The Gen-1 photonic chip laboratory demonstrations achieved 3.8±0.8×10-10 on-chip suppression and 8.70±1.1×10-8 raw contrast with a system-level free-space coupled input. We then describe the Gen-2 photonic chip update, which scales the main mesh from 9 to 16 input channels and from 72 to 240 thermo-optic phase shifters while adding improved high-efficiency normal incidence grating-couplers, routing, isolation and packaging. Finally, we use numerical wavefront-control simulations to quantify the benefits of the added degrees of freedom, including larger and deeper dark zones, faster convergence, improved narrowband performance, and DAC-resolution limits for achieving target contrast levels.