Method and apparatus for extending fiber transmission distance with multiple pre-emphases in optically amplified dwdm system

Abstract

A Dense Wavelength Division Multiplexed (DWDM) optical transmission system that compensates for unequal channel performance over an extended fiber transmission distance. The DWDM optical transmission system includes optical transmitters at a transmitter end of a transmission path for transmitting respective channels of information at different wavelengths, a first pre-emphasis device for performing a first pre-emphasis technique on the respective channels, an optical multiplexor for combining the respective channels into a multi-wavelength optical signal for transmission on a single transmission fiber, at least one optical amplifier for amplifying the optical signal along the path, at least one second pre-emphasis device disposed along the path for performing a second pre-emphasis technique on the respective channels, an optical de-multiplexor for separating the optical signal into its component channels, and optical receivers at a receiver end of the path for receiving and detecting the information carried by the respective channels. The first and second pre-emphasis techniques performed by the respective first and second pre-emphasis devices compensate for unequal channel performance along the transmission path over a desired fiber transmission distance.