LAUSR

Abstract A novel analytical approach is developed to evaluate the bit error rate performance (BER) of a DC biased optical coherent orthogonal frequency division multiplexing (DCO−CO-OFDM) transmission system with distributed Raman amplifier using single mode fiber (SMF) considering intensity modulation and coherent heterodyne detection. Analytical expressions are developed for optical SNR (OSNR) at the output of the fiber link along with IF-SNR and output SNR to evaluate the conditional BER performance for a given output of DCO-OFDM demodulator. Average BER is evaluated by averaging the conditional BER over the pdf of the output of DCO-OFDM demodulator. Results are evaluated in terms of average BER with different systems parameter viz. input signal power, pump power, local oscillator power, modulation index, number of OFDM sub-channel, fiber length and data rate. Results show that DCO−CO-OFDM optical transmission system offers better performance compared to CO-OFDM optical transmission reported earlier. It is further noticed that performance of an optical OFDM transmission link can be significantly improved by increasing the number of OFDM subcarrier and DC bias level. The results are found to be in conformity with the results of CO-OFDM reported earlier.