Unequal channel spacing 8×5 Gbps optical system utilizing different signal representations.

Data representations are important to communication networks; they convert the data bits into a signal form, which affects the system capacity, maximum bit rate, transmission distance, and different linear and nonlinear impairments. In this paper, we propose non-return-to-zero (NRZ), chirped NRZ, duobinary, and duobinary return-to-zero (DRZ) data representations with eight dense wavelength division multiplexing channels for transmitting a 5 Gbps data rate through a 250 km fiber length. The results of the simulation design are calculated at different equal and unequal channel spacings, and the quality factor is measured over a wide range of optical power. For equal channel spacing, the DRZ has a preferable performance with a 28.40 quality factor at 18 dBm threshold power, and the chirped NRZ has a preferable performance with a 26.06 quality factor at 12 dBm threshold power. For unequal channel spacing, the DRZ has a 25.76 quality factor at 17 dBm threshold power, and the NRZ has a 25.06 quality factor at 10 dBm threshold power.