Integrated optics for astronomical interferometry - II. First laboratory white-light interferograms

We report first white-light interferograms obtained with an integrated opti cs beam combiner on a glass plate. These results demonstrate the feasabilit y of single-mode interferometric beam combination with integrated optics te chnology presented and discussed in Paper I (Malbet et al. 1999). The demon stration is achieved in laboratory with off-the-shelves components coming f rom micro-sensor applications; not optimized for astronomical use. These tw o-telescope beam combiners made by ion exchange technique on glass substrat e provide laboratory white-light interferograms simultaneously with photome tric calibration. A dedicated interferometric workbench using optical fiber s is set up to characterize these devices. Despite the rather low match of the component parameters to astronomical constraints. we obtain stable cont rasts higher than 93% with a 1.54-mu m laser source and up to 78% with a wh ite-light source in the astronomical H band. Global throughput of 27% for a potassium ion exchange beam combiner and of 43% for a silver one are reach ed. This work validates our approach for combining several stellar beams of a long baseline interferometer with integrated optics components.