Title of Presentation: Faint Near-Neighbor Detection with a Fiber Nuller

Primary (Corresponding) Author: Gene Serabyn

Organization of Primary Author: NASA Jet Propulsion Laboratory

Abstract: Direct detection of light from exo-planets remains extremely difficult, except in a few limiting cases, because of the high contrasts and small angular separations involved. In this research, demonstration of a novel high-contrast hybrid coronagraph/interferometer is being pursued. The instrument, the “fiber nuller,” consists of a rotating nulling interferometer baseline within the envelope of a single-telescope aperture. After applying a pi phase shift between a pair of subapertures, the two beams are coupled directly to a single mode fiber, with no intervening optics, leading to a very simple interferometric beamcombiner. However, because only a single telescope is made use of, the instrument can also be described as a coronagraph. Regardless of nomenclature, the inner working angle of this approach is quite small. Such an instrument can thus not only provide a testbed for interferometric signal detection and demodulation approaches needed by nulling interferometers such as TPF-I, but it also provides a very competitive coronagraph. Initial laboratory fiber nulling results are now at the 10-6 (laser) and 10-4 (broadband) levels, more than sufficient for the next step of moving the experiment to the telescope. An initial fiber nulling experiment at Palomar is currently in the works for the spring of 2007.