High-resolution broadband integrated spectrograph for astronomical observation

Traditional astronomical spectrographs face significant challenges due to their large size, high complexity, and limited scalability. Here, we present an integrated spectrograph that achieves a footprint on the order of cubic centimeters, which is 3 orders of magnitude smaller than traditional astronomical instruments. The primary dispersive element is a silicon nitride ( Si 3 N 4 ) waveguide-array chip based on a cascaded phase-modulation architecture. The resolving power is above 25,000, and the bandwidth exceeds 180 nm, which can be extended to several hundred nanometers with optimized imaging optics. An astronomical observation is performed with the spectrograph, and infrared solar Fraunhofer lines were observed with Fe I at 1564.85 nm and 1565.29 nm, clearly resolved. This compact and scalable architecture provides a promising integrated solution for large-scale spectroscopic surveys, as well as other astronomical and space applications.