Patent ID: 7660537

Claim:
An apparatus for pre-equalizing an optical signal at a transmitter, comprising: a digital signal processor (DSP), for determining a target pre-equalized signal waveform associated with an expected distortion of the optical signal by a fiber link, wherein the DSP determines the target pre-equalized signal waveform by: dividing the fiber link into N segments, wherein N is an integer greater than one, wherein the N-th segment is associated with a receiver and the first segment is associated with a transmitter; and iteratively computing a plurality of pre-equalized signal waveforms for the respective plurality of segments; wherein the pre-equalized signal waveforms are computed beginning with the N-th segment and ending with the first segment in a direction from the receiver toward the transmitter; wherein, for the N-th segment, the pre-equalized signal waveform associated with the N-th segment is computed using as input a desired waveform to be received by the receiver; wherein, for each of the remaining N-1 segments, the associated pre-equalized signal waveform computed for a current segment is computed using as input the pre-equalized signal waveform computed for the previous segment; wherein the target pre-equalized signal waveform determined by the DSP is the pre-equalized signal waveform associated with the first segment; digital to analog converters, for converting in-phase and quadrature-phase components of the target pre-equalized signal waveform into analog waveforms; and an electro-optical modulator, for encoding the analog waveforms onto an optical carrier to form a pre-equalized optical signal; wherein the DSP adaptively determines the target pre-equalized signal waveform according to receiver signal quality information received via a communication link.