## 4 Results and Discussion  
In total, 15 DWDM channels with a spacing of 0.2 nm operating at the c-band, where each channel carries eight users, can be accommodated by the proposed hybrid system, a data rate of 40 Gbps and transmission power of 22 dBm transmitted over 105.075 km. The SMF with the following properties: cross effective area of 80 \(\upmu\)m\({}^{2}\) and chromatic and slope dispersion of 16.75 ps/nm\(\cdot\)km and 0.075 ps/nm\({}^{2}\cdot\)km was used to evaluate the performance of the hybrid system along with the DCF. The EOPM module is used to simultaneously modulate the signals' phase, which are carried by the DWDM channels to eradicate the intra-channel FWM effect. The eradication of intra-channel FWM occurs because its contributions coming from different pulses acquire a relative phase shift. By optimizing this phase shift, destructive interference can be obtained between different intra-channel FWM contributions. The key EOPM parameter is the phase deviation, which determines the relative phase shift of the intra-channel FWM contributions. In Ref. [19], the optimum phase deviation of the EOPM module was set at \(2\pi/3\). To guarantee the avoidance of ISI, the authors in [19] proposed the squeezing method, where its principle is to squeeze the identification sequence code interval into less than a bit duration; therefore, in this paper we implemented the squeezing method where the code sequence interval was squeezed into 25% of bit duration to guarantee the avoidance of the ISI. In this paper, the simulation was conducted using co-simulation of OptSim and MATLAB software utilizing SMF and DCF with the properties stated in Table 1.  
Based on the mathematical model presented in Section 3, the strength of the FWM depends not only on the fiber characteristics but also on the optical sequence code properties, such as code length, weight, and auto/cross correlation, where longer sequence code lengths are recommended for achieving better performance. Therefore, the identification sequence code not only has a positive/negative impact on MAI but also has an impact on the effect of FWM. Whether it impacts positively or negatively depends on the properties of the optical sequence code. The MD code is one of the best candidates to use as a signature sequence code for the optical CDMA users in our proposed hybrid system. The performance of the proposed hybrid system for CSRZ, MDRZ, and RZ modulation formats in terms of the BER as a function of transmitted power at \(w=3\) and \(F=24\) for the MD sequence code are shown in Figure 2, Figure 3, and Figure 4, respectively. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Value** & **Parameter** & **Value** \\ \hline Number of channels & N = 15 & Dispersion slope for SMF & 0.075 ps/nm\({}^{2}\cdot\)km \\ Number of users per channel & K = 8 & Cross effective area for SMF & 80 \(\upmu\)m\({}^{2}\) \\ Channel spacing & 0.2 nm & Length of DCF & 15.075 km \\ Data rate per channel & 40 Gbps & Attenuation for DCF & 0.5 dB/km \\ Data rate per user & 5 Gbps & Dispersion for DCF & \(-100\) ps/nm\(\cdot\)km \\ CW DFB Laser launch power & 9.8 dBm & Dispersion slope for DCF & \(-0.45\) ps/nm\({}^{2}\cdot\)km \\ Total insertion losses & 30.8 dBm & Cross effective area for DCF & 22 \(\upmu\)m\({}^{2}\) \\ Preamplifier gain & 30 dB & Nonlinear refractive index & 2.6 \(\times\) 10\({}^{-20}\) m\({}^{2}\)/W \\ Total transmitted power to the fiber & 22 dBm & Max nonlinear phase shift & 3.14 mrad \\ Length of SMF & 90 km & Phase deviation of EOPM & \(\varphi_{\text{EOPM}}\)= \(\frac{2\pi}{3}\) \\ Attenuation for SMF & 0.2 dB/km & Length and weight of the & F = 24, w = 3 \\ Dispersion for SMF & & sequence code & 16.75 ps/nm\(\cdot\)km \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Hybrid System Properties. Figure 3: The Average BERs versus Transmitted Power for Four Random Channels (MDRZ). Figure 2: The Average BERs versus Transmitted Power for Four Random Channels (CSRZ).