## 6 Simulation Results and Analysis  
In this section, the simulation results of the RIS-aided mixed RF/FSO-based system under the influence of various parameters are provided. Subsequently, Monte Carlo simulations are performed to further verify the accuracy of the simulated numerical results. The following parameters are assumed in the RF link: \(d_{SJ}=d_{SR}=d_{SE}=10\) m, \(m_{SR}=m_{SE}=2\). The instantaneous SNR of this link is \(\gamma_{SR}=15\) dB. In the interference link, the number of reflecting elements is N = 3, and the average interference noise ratio is 1 dB, \(m=3\), \(\Omega=1\), \(\lambda=\rho=0.4\), and \(d_{I\mathcal{R}^{\prime}}=d_{R^{\prime}E}=10\) m. Following are the parameters of the FSO link: the FSO link distance is 1 km, the wavelength is 758 nm, the refractive index structure constant is \(C_{n}^{2}=2.1\times 10^{-14}\), the instantaneous SNR of the FSO link is \(\gamma_{RD}=20\) dB, and the optical wave number is \(k=2\pi/\lambda_{1}\). Additional parameters include the instantaneous SNR of the eavesdropping link \(\lambda_{SE}=-10\) dB, \(\overline{\gamma}_{RD}=20\) dB, \(\xi=6.7\), \(\tau=1\), \(M_{j}=4\), and the target secrecy rate \(R_{s}=0.01\) nat/s. In the following simulations, the above values are used without additional explanation. In the calculations of the generalized Laguerre orthogonal numerical integration method, \(j\) is set to 30 to make the series converge. The Monte Carlo simulation results are provided in order to verify the validity of the analytical expressions. The numerical results are closely aligned with the simulation results, which verifies the accuracy of the expression. Figure 2 shows the correlation between the RF link instantaneous SNR \(\lambda_{SR}\) and SOP under the influence of different time-switching factors with or without the RIS assistance. The results show that the system SOP decreases as \(\lambda_{SR}\) increases. The value of SOP when \(\lambda=0.7\) is lower than that when \(\lambda=0.3\), irrespective of whether the RIS is introduced or not. This is because as the time switching factor increases, the energy storage time becomes longer and the jamming effect of the transmitted jamming signal is better. Consequently, the system SOP was reduced significantly. Next, keeping the time switching factor of the system fixed and \(\lambda_{SR}=35\) dB, \(\lambda=0.3\), RIS is introduced in the mixed system and compared with the SOP of the system before its introduction. The SOP values before and after the introduction of RIS are about 5.02 \(\times\) 10\({}^{-6}\) and 7.24 \(\times\) 10\({}^{-7}\), respectively. They differ by an order of magnitude, indicating that incorporating RIS can decrease SOP to improve security performance. Similarly, when \(\lambda_{SR}=35\) dB, \(\lambda=0.7\), the SOP values before and after the introduction of RIS are about 2.38 \(\times\) 10\({}^{-6}\) and 8.45 \(\times\) 10\({}^{-8}\), respectively. Thus, they differ by two orders of magnitude. Therefore, as \(\lambda\) increases, the addition of RIS noticeably enhances the mixed system secrecy performance. Figure 3 shows the correlation between \(\lambda_{SR}\) and the RF/FSO system SOP under the influence of different energy conversion efficiency values with or without the RIS assistance. As Figure 3 shows, the RF/FSO system SOP gradually diminishes with the \(\lambda_{SR}\) rises. Regardless of whether the RIS is introduced in the mixed system, the SOP of the system is obviously lower for \(\rho=0.9\) compared to that with \(\rho=0.5\). This is because as the energy conversion efficiency increases, the jammer stores more energy, the quality of the jamming signal is higher, the rate limit on the receiver side of the eavesdropper is enhanced, and the secrecy performance is better. When \(\lambda_{SR}=35\) dB, \(\rho=0.5\), the SOP values before and after the introduction of RIS are about 4.86 \(\times\) 10\({}^{-6}\) and 1.42 \(\times\) 10\({}^{-6}\), respectively, which indicates that incorporating RIS can decrease the SOP to improve the security performance.