Properties of fiber optics for application in astronomical interferometry.

We tested such properties of single-mode and multimode fiber optics that are relevant for use in a long-baseline astronomical interferometer, and we give quantitative values for modulation, transmission, and stability of the fiber optics as measured in a Mach-Zehnder interferometer configuration. Only polarization-maintaining single-mode fibers gave satisfying results. Good preservation of modulation and ease of beam combining are strong features of these fibers, whereas the light losses that are due to imperfect coupling may present a serious problem.