Optical ring network system having a plurality of node apparatuses connected in a ring

摘要

An optical network ensures substantially same received optical powers even if optional optical paths are connected between node apparatuses in a ringed optical network, and to provide a node apparatus for use in the network. The optical ring network system includes a plurality of node apparatuses each sending out wavelength division multiplexed optical signals; an optical transmission line connecting the plurality of node apparatuses in a ring; and at least one optical amplifier disposed on the optical transmission line, wherein the sending power of optical signals to be inserted at each of the plurality of node apparatuses is set such that the received levels of the optical signals sent out from the plurality of node apparatuses and received at the input of the optical amplifier become equal.