US Patent 9197322 Digital optical spectral shaping

A method and system for generating an optical channel signal for transmission through an optical fiber link of an optical communications system. A digital filter processes an input data signal using a compensation function and a shaping function to generate a pair of multi-bit sample streams representing a target optical E-field envelope of the optical channel signal. A modulator modulates an optical carrier light using the pair of multi-bit sample streams to generate the optical channel signal. The compensation function is designed to at least partially compensate impairments of the optical fiber link. The predetermined shaping function is designed to modify a baseband spectrum of the target optical E-field envelope.