Experimental Analysis of Receiver Performance of Optical CDMA System Using DPSK and OOK Modulation Through Balanced Detection and Optical Thresholding Techniques

In this paper, the performance of optical code division multiple access (OCDMA) system is studied using differential phase shift keying (DPSK) with balanced detection (BD) and optical thresholding. For the OCDMADPSK receiver, the performance parameters (i) bit error rate (BER), (ii) receiver sensitivity and (iii) spectral efficiency for asynchronous multiple access network are evaluated and compared with on off keying (OOK) modulation. Analysis of the system performance limiting issues such as multiple access interference (MAI) and signal interference beat noise (BN) are carried out and genuine approximation model is derived for the comparison. The optical signal to noise ratio (OSNR) is measured for various lengths of the fiber with dispersion compensated erbium doped fiber amplifier (DC-EDFA). The numerical results shows (i) 3dB receiver sensitivity improvement for BD (ii) better tolerance of 6dB to MAI and BN of DPSK over OOK – OCDMA and (iii) additional system gain and network security through OCDMA encoding / decoding (E/D) technique.