Design and simulation of a photonic lantern-inspired astrophotonic chip for spectral sensing

Abstract

Compact astrophotonic sensors can trade general-purpose spectral coverage for task-specific wavelength discrimination in a small integrated footprint. Developed with the Mazin Lab at UC Santa Barbara, this chip couples a single-mode input into a multimode interference region and seven-port fanout, producing wavelength-dependent output power fingerprints for spectral retrieval. Using ANSYS Lumerical FDTD simulations in silicon nitride, we compare symmetric and staggered-release geometries and quantify throughput, wavelength-dependent changes in the seven-port output distribution, and sensitivity near a 745 nm design point. We optimize over the tested geometric parameter space and identify designs with improved throughput and wavelength discrimination, including increased throughput-weighted Fisher information relative to the baseline. These results suggest that lantern-inspired integrated photonics can enable compact, task-specific spectral sensors for astrophotonic applications.