Six-Telescope Ultrafast Laser Inscribed Beam Combiner for Stellar Interferometry in the J-Band

Stellar interferometry requires coherent combination of two or more beams from identical telescopes separated by long baselines. This poses high demands on the optical alignment precision and stability. Here, photonic components are particularly useful due to their compact design and their potential to be less sensitive to environmental changes, such as vibrations. Unlike 2D planar photonic beam combiners fabricated using lithographic processes, beam combiners made with ultrafast laser inscription (ULI) can have 3D structures, enabling waveguide designs that do not significantly scale in size with the number of telescopes. A single ULI chip can have multiple beam combiners with different properties, as well as redundancies.