Brightness of a phase-conjugating mirror behind a random medium
  A random-matrix theory is presented for the reflection of light by a disordered medium backed by a phase-conjugating mirror. Two regimes are distinguished, depending on the relative magnitude of the inverse dwell time of a photon in the disordered medium and the frequency shift acquired at the mirror. The qualitatively different dependence of the reflectance on the degree of disorder in the two regimes suggests a distinctive experimental test for cancellation of phase shifts in a random medium. 
J.C.J. Paasschens (Philips Research Laboratories, Netherlands), P.W.   Brouwer, and C.W.J. Beenakker (Leiden University, Net...