Combined impact of SRS, FWM and ASE noise in UDWDM/DWDM long-haul communication systems using EDFAS

Abstract

In this paper, the combined impact of SRS, FWM and ASE noise in center channels of 7-, 15-, 31- and 63-channel UDWDM/DWDM long-haul multi-span optical fiber communication systems using different numbers of EDFAs has been analyzed with simulations. UDWDM/DWDM systems with varying system parameters, i.e. channel input powers, channel spacing values, multi-span fiber lengths and numbers of EDFAs, have been taken into account in simulations. Comparative OSNR simulation results satisfying a minimum 23 dB OSNR criterion under the combined impact of SRS, FWM and ASE noise have been presented and evaluated. OSNR vs channel input power simulation results show that FWM becomes the most dominant effect with respect to SRS and ASE noise in UDWDM systems. Therefore, OSNR values decrease as channel input powers increase in multi-span UDWDM systems having 3.125 GHz and 6.25 GHz channel spacing values. However, both ASE noise and SRS become more dominant with respect to FWM in DWDM systems with 100 GHz channel spacing values. OSNR values increase as the channel input powers increase in those multi-span DWDM systems. Simulation results for OSNR vs channel spacing values show that OSNR values obtained in multi-span UDWDM systems increase as channel spacing values increase in the 3.125 GHz-6.25 GHz range. This is due to the decrease in FWM crosstalk, which has a dominant effect in UDWDM systems, with increasing channel spacing values in those UDWDM systems. However, OSNR values obtained in multi-span DWDM systems decrease as channel spacing values increase in the 12.5 GHz-100 GHz range. This is due to the increase in ASE noise, which has a dominant effect in DWDM systems, with increasing optical filter bandwidths of those DWDM systems. OSNR vs channel length simulation results show that OSNR values generally decrease with increasing total fiber lengths and inter-amplifier fiber lengths in both UDWDM and DWDM multi-span systems. This is due to the FWM crosstalk and the ASE noise, which become more dominant with respect to the SRS as the total fiber length and inter-amplifier fiber lengths increase. Simulation results for OSNR vs number of EDFAs show that OSNR values obtained in multi-span UDWDM systems having 3.125 GHz channel spacing values decrease with increasing numbers of EDFAs. However, OSNR values in multi-span UDWDM/DWDM systems having 6.25 GHz-100 GHz channel spacing range increase with increasing numbers of EDFAs. Simulation results provide important clues for the design and implementation of reliable long-haul UDWDM/DWDM systems.