An optical receiver may receive input signals carried by sub-carriers, and may apply test phases to each input signal. The optical receiver may determine error values, associated with test phases, for each input signal. The optical receiver may calculate updated metric values, associated with the test phases, for a particular input signal, based on a first error value and a second error value. The first error value may be associated with a first sub-carrier, and the second error value may be associated with a second sub-carrier. The optical receiver may compare the updated metric values associated with the particular input signal, and may determine a test phase that represents an estimated phase, associated with the particular input signal, based on the comparison. The optical receiver may determine a phase estimate value based on the test phase, and may provide the phase estimate value to modify the particular input signal.