Patent ID: 7835645
Filing Date: 2010-11-16
Classification: H04J

Abstract:
1. An optical circuit structure for realizing a higher-order node in an optical transmission network comprising: (a) a number N of bidirectional remote ports, each remote port operable to receive a respective one of a number N of optical receive wavelength division multiplexed signals (R-WDM signals) each having a set of optical receive channels, each remote port operable to output a respective optical transmit wavelength division multiplexed signal (T-WDM signal) having a set of optical transmit channels, wherein a respective optical center wavelength is assigned to each receive channel or transmit channel, and wherein the number N is greater than or equal to three; (b) a number M of bidirectional local ports, M being greater than or equal to one and less than or equal to N, each of the M local ports being associated with a respective selected one of the N remote ports, each local port being operable to receive one or more optical add channels and output one or more optical drop channels; (c) one or more optical drop channel circuits for feeding selected optical channels of respective ones of the N R-WDM signals as drop channels to respective selected ones of the M local ports, and for guiding the respective R-WDM signals as cross-connect wavelength division multiplexed signals (cross-connect WDM signals) toward the relevant remote port, each drop channel circuit including an optical splitter unit splitting the respective R-WDM signal and an optical demultiplexing unit connected to an output port of the optical splitter unit; (d) a number N of optical add and cross-connect circuits for guiding the respective R-WDM signals as cross-connect wavelength division multiplexed signals (cross-connect WDM signals) toward the relevant remote port, and for generating a respective one of the optical T-WDM signals for each of the N remote ports, each optical acid and cross-connect circuit for extracting certain receive channels as pass-through channels from the R-WDM signals of one or more of the other remote ports and combining together with the selected ones of the one or more add channels optionally added to the respective T-WDM signal that can be output from the relevant remote port, each add and cross connect circuit comprising: