Patent ID: 8768178

Claim:
A high-speed coherent optical receiver comprising: an optical hybrid that mixes an optical input signal and an optical local oscillator signal; a photodetector that converts optical output from the optical hybrid into electrical signals; a transimpedance amplifier that amplifies the electrical signals, the transimpedance amplifier having a predefined input signal range; a digital receiver that generates one or more feedback signals using the amplified electrical signals; a feedback block that weights the one or more feedback signals; a tap that splits off a fraction of the optical input signal before it is input to the optical hybrid; a power measuring block, that measures the split off optical input signal; a feedforward controller that generates feed-forward signals based in part on the measured power for the split off optical input signal; and a controller block that generates a power control signal using both the feed-forward signals and the weighted one or more feedback signals, and the power control signal adjusts the local oscillator signal such that the electrical signals from the photodetector remain within the predefined input signal range of the transimpedance amplifier when the power of the optical input signal varies.