Abstract: A vehicle recognition device includes: an acquisition unit configured to acquire a value of a parameter relating to a degree of dirtiness of an in-vehicle LIDAR device detecting objects using light or a radiowave close to light; and a judgment unit configured to judge a state of the in-vehicle LIDAR device to be an abnormal state in a case in which the value of the parameter continuously exceeds a threshold during a first period, and the amount of change of the value of the parameter in a second period including a part or whole of the first period is within a reference range.

Abstract: An optical communication system is arranged to bring out potential capabilities of mode-division multiplexing (MDM). The optical communication system includes a hologram medium in which holograms are multiplex-recorded so as to correspond to respective spatial modes of signal light transmitted by a multi-mode fiber (MMF). A phase plate modulates phases of the respective spatial modes so as to reduce a spatial overlap between the spatial modes, and is provided on a side of the hologram medium on which signal light enters the hologram medium.

Abstract: An object of the present invention is to bring out potential capabilities of mode-division multiplexing (MDM). An optical communication system includes a hologram medium (1) in which holograms are multiplex-recorded so as to correspond to respective spatial modes of signal light transmitted by a multi-mode fiber (MMF) (2). A phase plate (4) which modulates phases of the respective spatial modes so as to reduce a spatial overlap between the spatial modes is provided on a side of the hologram medium (1) on which side the signal light enters the hologram medium (1).