Characteristics of all-optical 2R regenerators based on self-phase modulation in high-nonlinear fibers

Summary form only given. All-optical re-amplification and re-shaping (2R) is a key technology that enables long distance transmission of high-bit-rate data. A simple all-optical 2R scheme was proposed by Mamyshev (1998) This 2R scheme is based on self-phase-modulation (SPM) in a fiber and a subsequent optical filtering at a shifted frequency. The amplitude fluctuations in '0s' and '1s' can be effectively suppressed. Although simple in concept, several important questions need to be answered: (i) what is the optimum fiber length and dispersion; (ii) how to minimize power budget; and (iii) what is the limitation due to stimulated Brillouin scattering (SBS). The SBS effect should be considered in the SPM based spectral broadening process. We propose two 2R regeneration designs. Dithering the transmitter laser frequency effectively broadens the pulse spectral bandwidth and increases SBS threshold in the first design. The second design uses an isolator to connect two high-nonlinear fibers, HNLF-1 and HNLF-2. The dispersion of HNLF-2 can be smaller so the extra loss introduced by the isolator can be tolerated.