Patent ID: 8023833

Claim:
An optical receiver, comprising: an optical delay line interferometer comprising an optical input port that receives a modulated optical input signal carrying a baseband signal, a first optical path that receives a first part of the received modulated optical input signal, a second optical path that receives a second part of the received modulated optical input signal, and an optical output port that combines light from the first and second optical paths to cause optical interference and produces a constructive optical output signal having a constructive transfer function and a destructive optical output signal having a destructive transfer function; a first optical detector that converts the constructive optical output signal into a first electrical signal; a second optical detector that converts the destructive optical output signal into a second electrical signal; a signal combiner that combines the first and second electrical signals to produce a difference between the first and second electrical signals that represents a recovery of the baseband signal in the received modulated optical input signal; a data estimator that processes the difference between the first and second electrical signals to recover digital data bits from the difference produced by the signal combiner; a signal gain imbalance control unit that controls a difference between amplitudes of the first and second electrical signals at the signal combiner; and a feedback circuit configured to access a lookup table of imbalance values for the imbalance between amplitudes of the first and second electrical signals that correspond to various optical filtering conditions for the modulated optical input signal, obtain from a host system parameters of a current optical filtering condition under which the modulated optical input signal is to be transmitted to the optical receiver, use the lookup table to obtain a respective imbalance value for the current optical filtering condition, set the imbalance between amplitudes of the first and second electrical signals to the respective imbalance value obtained from the lookup table, receive information on signal quality of the recovered digital data bits, and produce a second feedback control signal to the signal gain imbalance control unit in response to the signal quality to maintain the imbalance between amplitudes of the first and second electrical signals at the respective imbalance value obtained from the lookup table.