Analysing and Improving T.O.D Effect on Ultra Long Haul High Bit Rate Optical Communication System

Subbulakshmi K, Sidharthraj R.S

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Third-order Dispersion (TOD), Amplified Spontaneous Emission (ASE), SSMF- DCF System.


This project presents a comprehensive investigation on pulse distortions due to the third-order dispersion (TOD) on ultra-high speed long-haul single channel optical fiber communication system using Optical fiber System. The optical communication system consists of dispersion-managed line with periodic amplification by Er-doped fiberamplifiers. The presence of the TOD introduces broadening and an additional temporal shift on the propagating pulse. The impact of TOD is observed at the receiving end of transmission line considering the variation of different factors such as transmission reach, bit rate, duty cycle, pulse shape and fiber type. Only self-phase modulation, second and third order dispersion, fiber loss, and amplified spontaneous emission (ASE) noise are considered here. BER performance is also observed considering receiver noise. The numerical result shows that temporal effect on pulse center decreases in the case of NRZ Gaussian pulse while using SSMF-DCF system and when both group velocity dispersion and TOD effects are considered. At first, pulse broadening due to GVD and TOD has been observed by varying bit rates from 40 Gb/s to 160 Gb/s. Then temporal shift of pulse center position is investigated by varying transmission distance, bit rate, duty cycle, input pulse shape and different transmission models for DM systems. Finally, performance of input pulses such as Gaussian and super-Gaussian pulses is evaluated by varying bit rates from 40 Gb/s to 160 Gb/s. Fiber chromatic dispersion, SPM and receiver noises are taken into account for the numerical calculation. DM transmission line is considered for each scheme. A PRBS of length 27−1 is used to propagate through the optical fiber. The presence of the TOD causes pulse broadening, long oscillatory tail as well as introduces a temporal shift to pulse irrespective of shape. With the increase of bit rate, temporal shift of pulse center increases. Pulse center position also changes with the variation of duty cycles and it is found that temporal shift decreases with duty cycle. Time shift of pulse also occurs depending on pulse shape and fiber type.