Investigation of suitable cascaded arrangement of conventional optical amplifiers for DQPSK modulated UD-WDM system at a channel spacing of 12.5 GHz

Optical amplifiers are very essential part of any optical fiber communication system for attenuation free transmission of signals. For our research work, a 420-channel ultra-dense wavelength division multiplexing system with 12.5 GHz channel spacing and a data rate of 100 Gbps per channel is designed based on advanced modulation technique namely differential quadrature phase shift keying and investigated the suitable cascaded arrangement of the conventional optical amplifiers such as erbium-doped fiber amplifier, semiconductor optical amplifier (SOA) and RAMAN amplifier. The investigation has been done based on some parameters such as receiver sensitivity, probability of error, quality factor (Q-factor), eye closure, received output power, and bit error rate (BER) with varying distances and applied input power. The simulation results have reported that the cascaded arrangement of the RAMAN-SOA-RAMAN amplifiers is the best suitable arrangement for signal transmission using an optical fiber communication system with less effect of attenuation. Minimum receiver sensitivity of - 30 dBm, minimum probability of error of 0.33, minimum eye closure value of 1.24 dB, and maximum Q-factor of 16.5 dB with varying distances have been reported. Also, the minimum BER of 10(-11) and maximum output power of - 31 dBm with varying applied input power has been reported.