An optical receiver capable of substantially measuring the phase and amplitude of a received intensity- or amplitude-modulated optical signal by performing digital-signal processing. In an example embodiment, a DSP of the receiver operates to reduce the detrimental effects of relative phase noise between the optical reference oscillator and optical carrier based on an optical pilot present in the received optical signal. The DSP may employ a sequence of digital filters configured to select a signal component that represents a non-vestigial modulation sideband and then perform signal equalization thereon. The signal equalization may include but is not limited to dispersion compensation. In some embodiments, the optical receiver can be a direct-detection optical receiver. In an example embodiment, the optical reference oscillator and optical carrier are generated using two respective independently running lasers that may or may not be co-located.