Patent ID: 6907195

Claim:
A WDM optical network, comprising: a plurality of optical transmitters, each optical transmitter generating a data signal sent over a respective one of a plurality of signal channels, the plurality of signal channels being divided into a number of sub-bands where each sub-band includes at least two signal channels; a plurality of substitute signal transmitters, the number of substitute signal transmitters being equal to the number of sub-bands, each substitute signal transmitter generating a substitute signal which provides loading in a corresponding sub-band; a combining circuit which combines the data signals output from the plurality of optical transmitters and the substitute signals output from the plurality of substitute signal transmitters into a WDM signal, a monitoring circuit which detects the wavelengths and power levels of each data signal in the WDM signal; a control circuit, coupled to the monitoring circuit, which determines if a signal channel is unused or inoperable based on the detected wavelengths and power levels of the data signals detected by the monitoring circuit, if one or more signal channels is determined to be unused or inoperable, the control circuit identifies the sub-band of the unused or inoperable signal channel and turns on the substitute signal transmitter corresponding to the identified sub-band, wherein the control circuit adjusts the power of the turned-on substitute signal transmitter depending on the number of unused or inoperable signal channels in the identified sub-band; and, an optical transmission fiber which receives the WDM signal from the combining circuit.