Context : Recentely , an increasing number of scientific publications making use of images obtained with near-infrared long-baseline interferometry have been produced .
The technique has reached , at last , a technical maturity level that opens new avenues for numerous astrophysical topics requiring milli-arc-second model-independent imaging .
The Very Large Telescope Interferometer ( VLTI ) will soon be equipped with instruments able to combine between four and six telescopes .

Aims : In the framework of the VLTI second generation instruments Gravity and VSI , we propose a new beam combining concept using integrated optics ( IO ) technologies with a novel ABCD-like fringe encoding scheme .
Our goal is to demonstrate that IO-based combinations bring considerable advantages in terms of instrumental design and performance .
We therefore aim at giving a full characterization of an IO beam combiner in order to establish its performance and check its compliance with the specifications of an imaging instrument .

Methods : For this purpose , prototype IO beam combiners have been manufactured and laboratory measurements were made in the H band with a dedicated testbed , simulating a four-telescope interferometer .
We studied the beam combiners through the analysis of throughput , instrumental visibilities , phases and closure phases in wide band as well as with spectral dispersion .
Study of the polarization properties was also carried out .

Results : We obtain competitive throughput ( 65 % ) , high and stable instrumental contrasts ( from 80 % in wide band up to 100 % \pm 1 % with spectral dispersion ) , stable but non-zero closure phases ( e.g . 115 ^ { \circ } \pm 2 ^ { \circ } ) which we attribute to internal optical path differences ( OPD ) that can be calibrated .
We validate a new static and an achromatic phase shifting IO function close to the nominal 90 ^ { \circ } value ( e.g . 80 ^ { \circ } \pm 1 ^ { \circ } ) .
All these observables show limited chromaticity over the H band range .

Conclusions : Our results demonstrate that such ABCD-like beam combiners are particularly well suited for interferometric combination of multiple beams to achieve aperture synthesis imaging .
This opens the way to extending this technique to all near infrared wavelengths and in particular , the K band .