Experimental progress in single-mode cross-aperture nulling

Single-mode (SM) cross-aperture nulling (CAN) can be used to observe faint exoplanets closer to their host stars than classical coronagraphs can reach, and also to extend observations of coronagraphically detected exoplanets to longer wavelengths. CAN can be implemented on an existing coronagraphic bench with a small number of additional optics, which are based on simple technologies such as optical phase masks and SM fibers. Here we present recent laboratory CAN results showing point source null depths (leakages) of ~ 3.7  10-7. Such null depths are already sufficient for use in exoplanet detection using large ground-based telescopes, and further work should yield performance of interest to the space-based case.