Comparison of modulation formats for 40 Gb/s transmission in a 170 km link of the Kyatera Testbed

This paper presents a theoretical comparison among six types of modulation formats applied to a 40 Gb/s transmission through the 170 km long Kyatera Testbed (Campinas - Sao Carlos, State of Sa¿o Paulo, Brazil). The formats are: NRZ-OOK, 33% RZ-OOK, 33% RZ-AMI, NRZDPSK, and 33% RZ-DPSK. The performance comparison, in terms of bit error ratio, is made for two system configurations: single-channel and 4-channel WDM in the ITU-T 100 GHz channel-spacing grid. For the single-channel results, NRZ-OOK is the only format which has not presented adequate BER, whilst all others resulted in a BER lower than 10^-12, each one for a different range of transmitted power. For the WDM configuration, NRZ-OOK and CSRZ have not reached a satisfactory performance. The NRZ-DPSK has been the less impacted format in the WDM configuration in comparison to its results in the single-channel configuration.