Development of an on-chip double Bracewell nulling interferometer in the near-infrared for the CHARA array

Astrophotonics is advancing long-baseline nulling interferometry by enabling direct imaging and spectroscopy of faint astronomical objects including exoplanets and faint binary star systems. On-chip instruments, with footprints of only a few centimeters, maximize stability, feedback control, and design flexibility, while minimizing thermo-mechanical disturbances and cost. These advancements are poised to provide extremely high angular resolution with minimal noise, particularly in the near-infrared. The successful deployment of the on-chip Keck Interferometer Nuller (KIN), GLINT nuller on the Subaru telescope, and the recently commissioned VLTI’s Nulling Observations of exoplaneTs and dusT (NOTT) demonstrate the potential of such astrophotonic technologies. In the northern hemisphere, the Center for High Angular Resolution Astronomy (CHARA) Array, located at Mt. Wilson, is equipped with the world’s longest baseline in the near-infrared. CHARA provides an ideal platform for nulling interferometry at sub-milliarcsecond angular resolution by leveraging its existing adaptive optics and fringe tracking facilities. In addition, self-calibration techniques such as the double Bracewell architecture proposed by Angel and Woolf can enable starlight suppression in the range of 10⁻⁴ to 10⁻⁶ in broadband. In this poster, we present our simulations of various science cases motivating the development of an astrophotonic near-infrared H-band nulling beam combiner for the CHARA array. We will present a quantification of the achievable observations in the limiting magnitude, contrast, and angular separation parameter space.