Development status of the L’-band 4-telescope integrated optics nulling beam combiner for NOTT

As the high-contrast visitor instrument for VLTI, the NOTT aims to detect and characterize young exoplanets in the mid-infrared L' band through nulling interferometry. This report outlines recent advancements in component fabrication via ultrafast laser inscription on GLS samples. Laboratory characterization, conducted on a 4-spectral interferometric testbench, is the first detailed mid-infrared characterization of such a photonic chip in its complete four-telescope nulling configuration, demonstrates favorable throughput, achromatic splitting ratios, and self-calibrated nulling performance within the 3.65-3.85 µm range. These achievements align with the specific requirements of NOTT, marking significant progress in meeting its specifications for high-precision observations.