Performance evaluation of 40 Gb/s directly-modulated optical fiber communication systems

This paper introduces simulation of performance evaluation of 40 Gb/s optical fiber communication systems using directly modulated high-speed distributed feedback (DFB) lasers. Electrical signals of return to zero (RZ) and non-return to zero (NRZ) formats with 2
¹⁰
-1 pseudorandom bit sequences are used to modulate the laser. A standard single-mode fibers (SSMF) is used. The laser has a blue shift of the lasing frequency and frequency chirps of 65 and 78 GHz under RZ and NRZ formats, which limit the fiber length to 2.51 and 1.37 km. Comparison of the results with those obtained by using a positive non-zero dispersion-shifted fiber (+D-NZDSF) is presented.