High GVD alone and combining SPM with GVD

High
speed communications and computations are the main industrial and academic
demands. Optical method is one of interesting alternatives for doing this purpose
1.Fiber
Optic communication offers higher frequency transmission of signals with
greater bit rate and larger data carrying capacity over a long distance. This
means of data transmission is with a lower loss and interference if compared to
the normal copper wire used in the electrical telecommunication systems. Optical
fiber is widely used in the application of internet communication technology in
developing countries largely due to its feasibility to transmit data over a longer
distance
2.In spite of all these benefits; optical fiber is not an ideal medium. The
quality of the optical pulse is degraded the system performances significantly due to various effects which
mainly include fiber loss, group velocity dispersion (GVD) and self-phase
modulation (SPM) 3.Basically, the linear effects (including the loss, GVD)
are responsible for changes in pulse shape while nonlinear effects (such as
SPM) are responsible for changes of pulse spectrum. The combination of
linear and
nonlinear
effects
leads to both the temporal and spectral changes of the pulse 4-5.

 The pulse degradation in the fiber limits the
maximum transmission distance and the transmission rate of the fiber link;
hence it is very important to analyze the pulse evolution behavior of the
propagating pulse in the fiber 3. The pulse propagation is modeled using
nonlinear Schrodinger equation (NLSE) 2. The chirp
parameter have important role in pulse propagation.
When C> 0 is referred to as up-chirp/positive chirp where the instantaneous
frequency increases linearly from the leading to the trailing edge On the other
hand, the frequency decreases linearly from the leading to the trailing edge
C< 0 and the same is termed as down-chirp/negative chirp 6.In anomalous dispersion regime ( ), the compression occurs for the up-chirped pulses, whereas the broadening takes place for the down-chirped pulses. The opposite situation happens for up- and down-chirped pulses propagating in the normal dispersion regime ) 4. In this research work is to investigate graphically the effect of Chirping with GVD, effect of SPM and the comparison of GVD alone and combining SPM with GVD in anomalous dispersion regime. The input pulse distribution is taken as a Gaussian pulse. In general, the non-linear Schrodinger Equation (NLSE) has been carried out by using a Split-step Fourier method (SSFM) for solving linear & non-linear effects. We implement code in MATLAB based on SSFM for Comparison of Gaussian optical pulses for different values of chirp parameter for anomalous dispersion and normal dispersion regime, how the Chirp parameter influences pulse broadening, Nonlinear effect (SPM) on different propagation distance where the extra frequencies generated through SPM broaden the frequency spectrum of the pulse result in SPM induced symmetrical spectral broadening 7. And finally the comparison of pulse evolution with GVD alone and combining SPM with GVD in anomalous and normal dispersion regime has been analyzed.  

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