Recent advances in coherent optical communication

Recent progress in coherent optical communication, a field revived by advances in digital signal processing (DSP), is reviewed. DSP-based phase and polarization management techniques make coherent detection robust and practical. With coherent detection, the complex field of the received signal is fully recovered, allowing compensation of linear impairments including chromatic dispersion and polarization-mode dispersion using digital filters. In addition, fiber nonlinearities can also be compensated by using backward propagation in the digital domain.