Techniques for nonlinearity cancellation into embedded links by optical phase conjugation

One of the main causes of signal degradation in high-bit-rate transmission systems is the interplay between fiber nonlinear effects and dispersion. Different techniques to compensate nonlinear effects in transmission systems, by using an optical phase conjugator, have been proposed in the literature. In this paper, two different innovative setups allowing nonlinearity cancellation in an embedded link are disclosed. The proposed schemes are simpler than those previously described and strongly improve systems performances. The physical mechanism allowing nonlinearity compensation is depicted, and the effectiveness of the proposed solutions is numerically demonstrated. Moreover a new practical method, useful for performance optimization of systems including a phase conjugator, is presented. Results apply to any bit-rate and modulation format.