The analysis showed an error-free operation, i.e., BER>1×10 -13. This link was planned on C-band and employed modulation technique of dual-polarization quadrature phase shift keying (DP-QPSK). Another study has simulated a 400 Gb/s unamplified WDM system over a distance of 40 km through a single-mode fiber. The power penalty of transmission in each channel was less than 2-dB while bit error rate (BER) was reported as 10 -10. A 40-Gb/s WDM system for the distance of 400 km was demonstrated using cascaded chirped fiber grating to compensate the dispersion. The signal to noise ratio (SNR) of 23.4 was achieved for the distance of 1200 km through a WDM link. In a study, a long-haul WDM link was designed using 224 Gb/s polarization-multiplexed 16-QAM. There are some articles that have studied high bit rate systems using WDM technology. According to the ITU-T standards, the channels are separated by a spacing of 100 GHz.
The DWDM systems operate at a central wavelength of 1550 nm due to the low attenuation. Introduction Dense wavelength division multiplexing (DWDM) is a technique by which multiple optical signals may be transmitted through optical fibers with closely spaced wavelengths. More research works are needed to evaluate the parameters that affect on the quality of the DWDM optical systems.ġ. The eye-diagrams showed an ideal quality for the received signals. The maximum quality factor of 20.7 and minimum bit error rate of 7.6×10 -95 are obtained at wavelength of 1552.5 nm. The quality of the network was estimated by using the eye-diagrams of the received signals. All simulations have been run by using Optisystem software. An EDFA and a DCF have been used for amplifying signals and compensating pulse dispersion, respectively. To this aim, we have assumed a link of 10 spans with a length of 100 km fiber for each span. In this study, we have simulated a 160 Gb/s DWDM network with transmission power of 0 dBm, using NRZ encoding technique through a 32-chanels optical transmitter over a distance of 1000 km. This modulation technique has the capability of transmitting several wavelengths through a single optical fiber. Growing demands of the internet users is one of the reasons that lead using dense wavelength division multiplexing (WDM) networks to transmit optical data.