The use of Carrier Suppressed Non-Return to Zero (CSNRZ) and Carrier Suppressed Return to Zero (CSRZ) modulation formats in Dense Wavelength Division Multiplexing (DWDM) channels at 1 Gb/s and 10 Gb/s is investigated. The results of simulated analysis using Differential Quadrature Phase Shift Keying (DQPSK) and Offset Quadrature Phase Shift Keying (OQPSK) formats are presented. We demonstrate that Stimulated Brillouin Scatteriring (SBS) is a major contribution of the back-scattering signal. At bit rate of 1 Gb/s and 10 Gb/s, CSRZ-OQPSK modulation format has a low threshold for SBS signal generation. For a data rate of 1 Gb/s, high SBS threshold of 19.76 dBm for CSRZ-DQPSK is recorded. The results can be used to suppress SBS in high power lasers which could be useful in high bit rate signal transmission.
 Ya-Ya, M., Xin-Zhi, S., Chong-Qing, W., Tian-Yong, Z., & Ying, W. (2015). Experimental Investigation of All-Optical NRZ-DPSK to RZ-DPSK Format Conversion Based on TOAD. Chinese Physics Letters, 32(11), 114204
 Chen, L. R., & Wang, J. (2012). All-optical RZ-OOK to RZ-BPSK conversion with multicasting based on XPM in highly nonlinear fiber. Optics Communications, 285(16), 3459-3465
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.