Optical fibers in astronomical interferometry

Single-mode fibers can be used in stellar interferometry to recombine independent telescopes coherently, w here they provide substantial advantages over conventional optics. In single-mode waveguides light propagation is forced to follow the structure of the fundamental mode and the spatial turbulence of the atmosphere is filtered out. This enables a gain of almost one order of magnitude in the accuracy of fringe-visibility measurements. A fiber recombination unit is installed at the IOTA interferometer on Mt. Hopkins in Arizona and is now routinely used for scientific observations. Optical waveguides are also under consideration for other interferometric facilities. Tomorrow, interferometers with large telescopes will combine single-mode integrated optics and adaptive optics to provide maximum precision and sensitivity.