Integrated optics interferometric four telescopes nuller
  Nulling interferometry has been identified as a competitive technique for the detection of extrasolar planets. The technique consists in combining out-of-phase pairs of telescopes to null effectively the light of a bright star an reveal the dim glow of the companion. We have manufactured and tested with monochromatic light an integrated optics component which combines a linear array of 4 telescopes in the nulling mode envisaged by Angel & Wolf (1997). Our testbench simulates the motion of a star in the sky. The tests have demonstrated a nulling scaling as the fourth power of the baseline delay. 
Ronny Errmann, Stefano Minardi, Lucas Labadie, Felix Dreisow, Stefan   Nolte, and Thomas Pertsch
astro-ph.IM