We will present simulation and laboratory demonstration for a novel technique, multi-aperture fiber nulling (MAFN). The technique conbimnes nulling interferometry and high-resolution spectroscopy, taking advantage of the high spatial resolution brought by the nulling interometry and the high contrast brought by the high-resolution spectroscopy. We show that with current facilities such as the Large Binocular Telescope Interferometer (LBTI) and future extremely large telescopes (ELTs), direct spectroscpy of radial velocity detected planets can be studied in unpresedented details to understand their orgin of formation and search for biosignatures in their atmospheres.