Integrated Hybrid Sol-Gel Devices for Astronomical Interferometry

Astronomical interferometry is an active area of research and an increasing number of new conceptual ideas and designs are being proposed to achieve optimum astronomical instruments. In particular, integrated optics has a lot to offer in what concerns beam combination and control. In this paper, different examples of application of hybrid sol-gel integrated optics devices for fabrication of beam combiners for astronomical applications is given. For the multiaxial beam combiners, a UV laser direct writing unit is used for mask fabrication. The operation principles of the coaxial combiners were validated using an interferometric set-up. Differential polarization and differential dispersion effects were minimized in this set-up to avoid any error in the characterization of the beam combiners. In all the devices, fringe contrasts above 90% were obtained with a source with spectral bandwidth of 50 nm. These results demonstrate that hybrid sol-gel technology can produce devices with high quality, opening the possibility of rapid prototyping of new designs and concepts for astronomical applications.