To simplify an optical system necessary for transferring light beams from one laser to the photodetector of another cluster by providing an optical tunnel for constituting a single video from plural other videos.

Various light beams radiated by the exited laser of a transmission cluster are shielded and converged by a spherical lens and supplied to the input terminal of the optical tunnel 26 to form and image on the common face of an output terminal at a position where the array 28 of photodetectors 28A to 28I connected to the processor of the cluster. Especually when each processor of a first cluster tries communication with a different processor of a second cluster, nine exited lasers form nine individual beam patterns from each chip and these nine beams appears at the output terminal of the tunnel 26 as the nine individual beams to drive the nine detectors 28A to 28I of the array 28 connected to the nine processors of the second cluster.