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For the first time, a novel net gain analytical model of EDFA–Raman hybrid optical amplifier (HOA) is designed and optimized the various parameters using genetic algorithm. Our method has shown to be robust in the simultaneous analysis of multiple parameters, such as Raman length, EDFA length and its pump powers, to obtained highest possible gain. The optimized HOA is further investigated and characterized on system level in the scenario of 100×10 Gbps dense wavelength division multiplexed (DWDM) system with 25 GHz interval. With an optimized HOA, a flat gain of >18 dB is obtained from frequency region 187 to 189.5 THz with a gain variation of less than 1.35 dB without using any gain flattened technique. The obtained noise figure is also the lowest value (<2 dB/channel) ever reported for proposed hybrid optical amplifier at reduced channel spacing with acceptable bit error rate. [ABSTRACT FROM AUTHOR]

Highlights: [•] The influence of crosstalk induced by hybrid optical amplifiers has been examined. [•] It is observed that as the input power increases the crosstalk will also increase. [•] It is recommended that R–E is the best combination as compared to other HOA. [•] The investigation of crosstalk has also been done in 16 channel DWDM system. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, four modulation formats including nonreturn-to-zero (NRZ), nonreturn-to-zero raised cosine (NRZ-RC), return-to-zero (RZ), return-to-zero raised cosine (RZ-RC) DWDM system with different hybrid optical amplifiers are introduced. We show that NRZ-DPSK and RZ-DPSK degrade the performance when Raman amplifier is considered. The obtained results reported that RZ and RZ-RC DWDM system with Raman-EDFA provide better results and cover 1512 and 1260km of transmission distance, respectively, with acceptable quality factor (>15dB) and bit error rate (<10−9). Further, it is also confirmed that using the hybrid optical amplifiers is a best alternative to increase the span distance. [Copyright &y& Elsevier]

Summary: In this paper, we have proposed a high‐performance transmission system of 32 channels based on dense wavelength division multiplexing (DWDM) through an optical fiber link consisting of 110 km per span. To check the influence of nonlinear effects, we have considered phase modulation (SPM), cross‐phase modulation (XPM), four‐wave mixing (FWM), stimulated Raman scattering (SRS), and self‐steepening (SS) which limits the performance of optical communication systems. In the proposed system, each channel is modulated at 200 Gbps of dual‐polarization quadrature phase shift keying (DP‐QPSK) format, with a 50‐GHz grid yield whole data rate of 6.4 Tbps. The results have proved that the nonlinear phenomena degrade the performance of proposed optical fiber communication systems, and XPM has the most dominant effect, followed by SS, SRS, and SPM. The simulation was carried out with Optisystem 14 which is powerful software for modeling and simulation of optical fiber transmission. [ABSTRACT FROM AUTHOR]