## 2 Electro-Optical Basic Concept of Architectural Standard Modulation
### Electro-Optical Mixing Setup  
Figure 2 depicts the arrangement for the electro-optical upward conversion. In our investigation, the electrical interface of SOA1 introduces the intermediate frequency (IF) signal (data signal). The steady-state current and the modulated data photon are combined to control the SOA electrode. The bias current across both SOAs is set to 400 mA. Furthermore, the electrical interface of SOA1 is configured with 50 \(\Omega\) impedance. The laser source (LS) produces the data signal with specific parameters, such as a wavelength of 1545 nm and an average optical power of \(-15\) dBm. The Mach-Zehnder modulator (MZM) transforms the optical light (data signal) using the M-QAM (quadrature amplitude modulation) data format, supplied by an electrical subcarrier (auxiliary carrier) at its electrical interface at \(f_{IF}=0.5\) GHz. The electrical power of the incoming data modulation is set to 13 dBm at the MZM electrical port. For the experimental work, the IF signal can be generated using an arbitrary waveform generator (AWG) as indicated (1) in Figure 2, or for simulations, a Generation and Detection Module mentioned (2) in Figure 2 at the MZM electrical gate. Subsequently, the optical M-QAM modulated signal at the MZM output undergoes conversion to the electrical domain using the first photodiode (PD1) with a sensitivity of 0.85 A/W. This electrical signal is then subject to amplification through a 33 dB gain from the first low-noise amplifier (LNA1) before being introduced into the electrical port of the upper SOA (SOA1). Figure 2: Frequency up-mixing setup dependent on the SOA-MZI standard modulation approach. The optical devices are depicted in a greenish-blue color, while the electrical devices are represented in black. AWG: Arbitrary Waveform Generator, BER: Bit Error Rate, BERT: Bit Error Rate Tester, DSO: Digital Sampling Oscilloscope, LNA: Low-Noise Amplifier, ESA: Electrical Spectrum Analyzer, MZM: Mach-Zehnder Modulator, OA: Optical Attenuator, OBPF: Optical Band Pass Filter, OPC: Optical Pulse Clock, PD: Photodiode, PM: Power Meter, QAM: Quadrature Amplitude Modulation, VSA: Vector signal Analyzer, and \(V_{b}\): Bias Voltage. The employed AWG, sourced from Keysight Technologies, Inc. under the model M8194A [34], embodies an exceptional fusion of celerity, bandwidth, and channel density within a singular module. Meticulously crafted to fulfill the distinct requirements of M-QAM modulation formats, it excels, with sample rates reaching up to 120 gigasamples per second (GSA/s). Recognized as one of Keysight's high-velocity AWGs, the M8194A achieves a harmonious equilibrium between versatility and simplicity, ensuring seamless operation in both solitary and multi-channel configurations. Orchestrated by a personal computer (PC) via a universal serial bus (USB), the AWG module introduces the preferred M-QAM format at an IF or RF frequency using a specific code that delineates the number of states in the QAM data and the IF/RF frequency. In our exploration, we generate four QPSK as well as 4096-QAM formats at varying baud rates or symbol rates (SRs) of up to 10 gigabauds (GBd) or (GSymb/s). Noteworthy is the AWG's prowess in generating M-QAM data at heightened baud rates, extending impressively up to 100 (GBd). An optical pulse clock (OPC) with a wavelength of \(\lambda_{s}=1550\) nm generates the required sampling signal at a repetition rate of \(f_{s}=19.5\) GHz at a pulse width of 1.6 ps. This signal is connected to the SOA-MZI's Medium Port (MP) interface. This repetition frequency is also changed to \(f_{s}=100\) GHz in order to achieve terahertz up-mixing. Harmonics are shown in the electrical spectrum at \(H_{n}=nf_{s}\). By utilizing an optical attenuator (OAtt), electro-optical mixing is achieved by reducing the peak sampling power to \(-1\) dBm. Based on the information provided, it appears that the optimal electrical spectrum is obtained at this power level.