Patent ID: 7061657

Claim:
A multichannel optical communication system for transmitting optical signals via an optical fiber comprising: a plurality of individual WDM transmission channels; a CDM transmission unit disposed within at least one individual WDM transmission channel of said plurality, said CDM transmission unit comprising one or more CDM transmission channels; a number of individual WDM transmission channels of said plurality, each transmitting a WDM optical signal on a unique wavelength within a designated bandwidth; and said CDM transmission unit transmitting CDM optical signals within said designated bandwidth of said at least one individual WDM transmission channel a number of single frequency optical sources, each generating light within each individual WDM transmission channel transmitting said WDM optical signal, and a broadband optical source for generating light within said at least one WDM transmission channel transmitting said CDM optical signals; wherein said broadband optical source has a discrete spectrum with equally spaced individual spectral lines, a spectral spacing between said spectral lines exceeding an electrical detection bandwidth of transmitted CDM optical signals; and wherein said broadband optical source is a multimode laser comprising: a lasing medium; an optical filter for defining said designated bandwidth having a center wavelength at the center of said at least one individual WDM transmission channel; and an optical cavity having length L=c/2f 0 where c is the speed of light, f 0 is said spectral spacing between adjacent spectral modes of said broadband optical source.