# All-Optical Simultaneous Frequency Metamorphose Contingent on a Three Parallel SOA-MZIs Copula
## 4 Simultaneous Up-Conversion Characterization
The low frequency signal is assembled by a continuous-wave (CW) laser source. In addition, an optical MZM impelled by a module is used to modulate the low frequency signal at frequencies \(f_{m}\). This module is used to establish a variety of data types, such as the orthogonal frequency division multiplexing (OFDM) at \(f_{m}\). These optically low frequency signals are then shifted at higher frequencies subsequent to the harmonics of the pulsed signal at \(nf_{s}\). The low frequency signals have the same average power of \(-10\) dBm at the upper port of the SOA-MZI at wavelengths \(\lambda_{p}\), where \(p\) is the whole number that spans from one to three. The wavelength of the signal to be up-converted publicizes from \(\lambda_{1}=1445\) nm to \(\lambda_{3}=1447\) nm. The bias current inside the used SOA-MZIs for each SOA is 350 mA. The output mixed signals emerging from the external port of the SOA-MZIs are combined in an effort to achieve simultaneous up-conversion formulated on the three parallel SOA-MZIs. This simultaneous signal is optically filtrated by a filter called the optical band pass filter (OBPF) regulated at the wavelength of the sampling control signal of 1550 nm. At the receiver, the filtered signal is subsequently converted to the electrical one by a 100 GHz photodiode (PD) whose responsivity is 0.86 A/W. The low-noise amplifier  
Figure 3: Simulation setup for CG, BER, and EVM characterizations. OAtt: Optical Attenuator; MZM: Mach-Zehnder Modulator; PC: Polarization Controller; OBPF: Optical Band-Pass Filter; LNA: Low-Noise Amplifier; ESA: Electrical Spectrum Analyzer; OPC: Optical Pulse Clock; BER: Bit Error Rate; QAM: Quadrature Amplitude Modulation. (LNA) that has 33 dB gain is used to augment the power of the electrical mixed signal, which is monitored in an ESA to compute the conversion gain (CG) or through BER_EL-M-QAM module to identify the bit error rate (BER) values. Then, the error vector magnitude (EVM) is calculated from BER values as expounded in [20]. To corroborate the concept of the jointly mixing process dependent on the three parallel SOA-MZIs, the electrical spectrum measured by an ESA is propounded in Figure 4. It is noteworthy that the low frequency signals at \(f_{m}\) at the inner port of the employed SOA-MZIs are up-converted at \(nf_{s}+f_{m}\). In Figure 4, we can recognize thirty replicas at various mixing frequencies travelling from \(f_{s}-f_{3}=18\) GHz to \(5f_{s}+f_{3}=99\) GHz. Moreover, we can detect that the high frequency signals after shifting comprehend up to the fifth harmonic of the control pulsed signal. As cited in the mixing concept, the source IF signal at \(f_{1}\) at the inner port of the SOA-MZII, \(f_{2}\) at the input of the SOA-MZI2, and \(f_{3}\) at the upper port of the SOA-MZI3 are shifted at \(nf_{s}\pm f_{m}\) drawn on the three parallel SOA-MZIs relevance. The efficacious of the simultaneous shifted signals developed on the parallel SOA-MZIs link is assessed by measuring the conversion gain (CG). The simulated CG is delineated as the dissimilarity between the electrical power of the high frequency signals after mixing in dBm at \(nf_{s}+f_{m}\) and the one of the low frequency signal of each SOA-MZI in dBm at \(f_{m}\). It is only calculated for replicas at \(5f_{s}+f_{m}\) linked to the fifth harmonics of the pulsed signal as presented in Figure 4. In order to compare fairly with the theoretical work, the theoretical CG in Equations (4)-(6) is computed separately for each replica generated from different data signals. In Equation (2), the combined optical output power can be computed. The simulated and theoretical CGs are displayed in Figure 5, which shows a good arrangement between them. Figure 4: Electrical spectrum of the up-converted signal based on the sampling parallel SOA-MZIs using a standard modulation mode at mixing frequencies \(nf_{s}\pm f_{m}\) at the outward port of the SOA-MZIs after combination, filtering, photo-detection, and amplification.