Theory of Optical Rectification Effect in Metallic Thin Film with   Periodic Modulation
  We conducted theoretical and numerical investigations of the optical rectification (OR) effect in metallic structures with periodic modulation. A new formulation of the OR effect is presented, and the mechanism by which the OR effect is generated, which has been a controversial issue in previous studies, is clarified. We reveal that the OR effect is strongly enhanced by a combination of spatial variation of the metallic structure and local electric field enhancement. Our theory was numerically evaluated and agreed fairly well with experiment. 
Kurosawa Hiroyuki, Ohno Seigo, and Nakayama Kazuyuki
physics.optics