Investigation of modulator chirp and extinction ratio in different RZ- and NRZ duobinary transmitter modules for performance optimization

In this work we present a comparative investigation of modulator chirp and extinction ratio in different transmitter modules for 10 Gbps, 20 Gbps and 40 Gbps RZ- and NRZ duobinary transmission. For comparative analysis three types of transmission modules have been considered viz. push–pull configuration based on dual arm MZIM, delay-and-add circuit based single arm MZIM and a duobinary filter followed by single arm MZIM. For each case, the modulator chirp has been optimized with an extinction ratio of 20 dB. Investigation has been carried out to find extinction ratio of single arm MZIM used for RZ- and NRZ duobinary transmission that offers system performance comparable to dual arm MZIM at 10, 20 and 40 Gbps. The results help choosing the best suitable transmitter module with optimized modulator chirp and extinction ratio.