First results on an electro-optic visible multi-telescope beam combiner for next generation FIRST/SUBARU instruments

Integrated optic devices are nowadays achieving extremely high performances in the field of astronomical interferometry, as shown by the PIONIER and GRAVITY instruments. Progress remains to be made in order to increase the number of apertures/beams/channels to be combined (up to 9) and eventually ensure on-chip phase modulation (for fringe temporal scanning). We present a novel generation of beam combiners, based on the hybridization of two integrated optic devices: (i) one producing glass waveguides, that can ensure very sharp bend radius, high confinement and low propagation losses, with (ii) a lithium niobate device providing phase modulators and channel waveguides that can achieve on-chip, fast (> 100kHz) phase modulation. The aim of this work is to compare three different concepts for the new generation FIRST/SUBARU 9T instrument, in terms of transmission, birefringence, half-wave voltage modulation and spectral range.