OPTICAL COMMUNICATION SYSTEM

摘要

The present invention causes spatial-mode light emitted from an optical fiber (11), which is a multimode fiber, to pass through a photorefractive medium (13). The photorefractive medium (13) includes holograms for signal separation that are written by irradiation of the photorefractive medium with (i) guide light having a wave front identical to the wave front of signal light having a particular spatial mode and (ii) control light. The photorefractive medium includes holograms recorded in a multiplex manner with use of control light having different incidence angles in correspondence with respective spatial modes. For signal separation, irradiating the photorefractive medium (13) with control light (15) having a particular angle separates signal light having a spatial mode corresponding to the incidence angle of the control light (15).