1. An optical receiver comprising: an optical to electrical converter (OEC) to produce an electrical signal vector representing at least one of amplitude, phase, and polarization information of a modulated optical carrier transmitted through an optical channel with impairments; and a signal processor coupled to the OEC to process the electrical signal vector to compensate the impairments of the optical channel, the signal processor comprising at least an adaptive equalizer to generate an equalized output, a decision, and an error, the error being difference between the equalized output and the decision, the adaptive equalizer having an adaptation based on at least the error.