Utilizing Active Single-Mode Fiber Injection for Speckle Nulling in Exoplanet Characterization

Despite recent advances in high-contrast imaging techniques, high resolution spectroscopy for characterization of exoplanet atmospheres is still limited by our ability to suppress residual starlight speckles at the planet’s location. We have demonstrated a new concept for speckle nulling by injecting directly imaged planet light into a single-mode fiber, linking a high-contrast adaptively-corrected coronagraph to a high-resolution spectrograph (diffraction-limited or not). The restrictions on the incident electric field that will couple into the single-mode fiber give the adaptive optics system additional degrees of freedom to suppress the speckle noise on top of destructive interference. We are able to achieve a starlight suppression gains that are an order of magnitude better than conventional techniques in broadband light with minimal planet throughput losses.