Direct UV-Written Integrated Optical Beam Combiner for Stellar Interferometry

In this paper, we report the fabrication of an optical-beam combiner for stellar interferometry by means of direct ultraviolet (UV) writing. The component is shown to have good performance (fringe contrast > 95%, total loss ~0.7, -40-dB crosstalk, broadband operation covering at least the range 1.49-1.65 mum, and low differential chromatic dispersion). The overall performance exceeds that of similar components currently used for astronomical research. This result, combined with the fast-prototyping ability of UV writing, opens up new possibilities for the realization of highly optimized integrated-optical components for astronomical research