Аннотация:Diffraction of light of a visible spectral range by subwavelength metal gratings is investigated theoretically and experimentally. The diffraction efficiencies of the gratings made of various metals (Ni, Ag, Al, etc.) with different depths of the profile are calculated and measurements are carried out. It is demonstrated that under certain conditions an effect of plasmon resonance occurs, at which a complete absorption of the incident light takes place. It is demonstrated, that the influence of the incident beam width on the diffraction efficiency and the electric field profile of the reflected beam is significant for the incident angles, at which the plasmon resonance occurs. It is shown that the incident beam width must be larger than the propagation distance of the surface plasmon in order to couple energy effectively into the plasmon mode.