Abstract

Optical network systems with prolonged reach are required to cater the long distance located optical network units (subscribers). In this work, a DP-128 QAM based system is proposed with Optical Back Propagation (OBP) to cope up with nonlinear impairments in wavelength division multiplexed (WDM) systems. OBP module that consists of optical phase conjugator (OPC), Raman fiber amplifier (RFA) and erbium doped fiber amplifier (EDFA) is investigated in pre, post and symmetrical configuration. Ideal OBP conditions are simulated using Dispersion Compensation Fiber (DCF) as a RFA with dual directional pumping. Dual directional pumping shows better result than forward and backward pumping. Results revealed that system can cover 5100 km within acceptable BER (10-3) using symmetrical OBP with RFA dual bi-directional pumping. Proposed symmetrical OBP system provides enhanced performance as compared to other techniques such as single channel digital back propagation (DBP), wideband DBP, pre OBP with forward pumping, pre OBP with backward pumping, pre OBP with dual directional pumping, and post OBP with dual directional pumping.