Phase Space Distributions from Three-Port Couplers
  A wide class of phase space distributions of a single mode radiation field is shown to be directly accessible to measurement by linear symmetric three-port optical couplers. 
Matteo G. A. Paris, Alexei V. Chizhov, and Ole Steuernagel   (Arbeitsgruppe ``Nichtklassiche Strahlung'' der Max-Planck-Gese...