@article{MAKHILLJEAS2018132317215, title = {PSD Calculations of the Intrachannel Nonlinearity Distortion Using Quantum Description for M-QAM-Square Techniques}, journal = {Journal of Engineering and Applied Sciences}, volume = {13}, number = {23}, pages = {9985-9993}, year = {2018}, issn = {1816-949x}, doi = {jeasci.2018.9985.9993}, url = {https://makhillpublications.co/view-article.php?issn=1816-949x&doi=jeasci.2018.9985.9993}, author = {Mahdi,Ali Hadi and}, keywords = {Intrachannel nonlinearity,Power Spectral Density (PSD),M-QAM square systems,parameters,Gaussian pulses,intrachannel}, abstract = {In highly dispersive single-channel fiber, the optical signal propagation within channel leads to significant signal broadening and thereby, it interacts nonlinearly with a large number of neighboring signals. The overlap-states leads to create echo signals in "0" bit slots and amplitude jitter in "1" bits slots too that can significant limit the system performance due to increasing in a Bit Error Rate (BER). In this thesis, the Power Spectral Density (PSD) of the intrachannel nonlinearity distortion of a chirped Gaussian pulses is investigated theoretically using the small perturbation technique and the statistical quantum description of square M-QAM systems. Additionally, we provided an analytical expression using the perturbation coefficient matrix Xlmn (ω) of PSD to estimate a Signal to Noise Ratio (SNR). We assumed that the noise is Additive White Gaussian Noise (AWGN) and all transmitted signals undergo equal probability of distribution on coherent receiver where MATLAB programming are used to check out validity of analytical model. Our simulation shows that the intrachannel distortion is mitigated significantly by choosing of initial suitable parameters. Consequently, improving the SNR to acceptable values is achieved.} }