STAR COUPLER AND OPTICAL COMMUNICATION NETWORK

An optical coupler capable of reducing the number of terminals of a star coupler per node and allowing easy expansion of a network configured by star couplers. A star coupler of the invention has a plurality of terminals and allows an optical signal to be inputted to and outputted from a single terminal. The star coupler also has such a transfer characteristic that an input signal to an initially inputted terminal is not distributed as an output signal from the initially inputted terminal but distributed as output signals to its terminals other than the initially inputted terminal.