Patent ID: 7065297
Filing Date: 2006-06-20
Classification: H04B,H04J

Abstract:
1. An optical transmission system for performing WDM optical transmission, comprising: a plurality of nodes; and an optical transmission medium making connections between the plurality of nodes; wherein each of the plurality of nodes includes, an optical preamplifier which has an optical output, a gain, an operational mode, an ALC function for maintaining a level of the optical output constant, and an AGC function for maintaining the gain constant, where the operational mode of the optical preamplifier is changed from an ALC mode to an AGC mode after the gain is set in the ALC mode, an optical postamplifier which has an AGC function, an optical switch unit which performs an optical crossconnect operation, and a thru-light-shutoff control unit which makes a switch setting so as to shut off pass-through light in the optical switch unit and stop transmission of an optical signal having an unstable level to a next stage when the optical preamplifier operates in the ALC mode, and clears the switch setting when the operational mode of the optical preamplifier is changed to the AGC mode.