# Beyond 100G: All-Optical Processor for High-Capacity Access\(\sim\)Networks
## 5 Results and Discussion  
The performance evaluation of the AOP for 100G and 200G downstream PON traffic is detailed in Figures 4(a) and 5(a). To assess its performance, the AOP was tested both as a standalone module and in synergy with a minimum-complexity digital FFE. For benchmarking purposes, the proposed equalization techniques, as outlined in Table 1, were employed. As mentioned above, the machine-learning-based decider selects the optimum task for each use case. In the case of 100G PON, Task 1 is selected, which comprises the optical FFE, whereas, in the case of 200G PON, Task 2 (CCDF) is chosen. For both cases, BER results were acquired against transmission distance and against receiver optical power at specific points. For the case of 100G PON, it is evident from Figures 4(a) and 5(a) that the use of the AOP (Task 1) enhances the overall system performance compared to the digital 13 FFE. Furthermore, the synergy of the AOP with digital five-tap FFE increases the transmission distance under the FEC limit by an additional 6 km, achieving a total fiber reach of up to 36 km. In terms of power penalty, the use of the AOP increases the ROP by about 3 dB at the FEC limit compared to the standalone digital equalization method. The depicted eye diagrams further support these findings, showing much clearer and more distinct eye openings when the AOP is used, indicating a substantial improvement in signal quality. For the case of 200G PON, Figures 4(b) and 5(b) demonstrate that the AOP (Task 2) significantly enhances the system performance over digital equalization techniques. It is even more clear that, with the AOP alone, we can see a substantial performance boost, extending the transmission distance to 14 km instead of 11 km with the 21/3 DFE. This boosted performance is further enhanced by the addition of a five-tap FFE, making this optoelectronic solution reach a fiber distance of up to 17 km. Regarding the power penalty, the AOP combined with the digital 5-tap FFE reduces the power penalty by about 3 dB at the FEC limit compared to the 21-tap FFE and 3-tap DFE digital solution. The same applies to the power diagram, where we see an ROP improvement of 6 dB only with the processor, \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameters** & **Simulated 100G PON** & **Simulated 200G PON** \\ \hline Task (FFE/CDCF) & FFE & CDCF \\ Attenuators (dB) & 24, 9, 20, 30 & - \\ Phase Shifters (deg) & 0, 0, 180, 180 & 146, \(-88\), \(-158\), \(-71\) \\ Optical Delay Lines (ps) & - & 14, 16, 15, 24 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: ML decider output values. and a similar performance with the addition of a five-tap FFE. The eye diagrams for the 200G PON also show significantly improved signal integrity. Figure 7 illustrates the optical spectrum of the transmission system operating in two different cases (100G and 200G PON). Figure 7a shows the spectrum before AOP during Task 1, after the AOP, and before the receiver at 50 GBaud with an ROP of \(-14\) dBm. Figure 7b presents the spectrum at 100 GBaud with the same traces (the only difference being that, this time, the decider goes with Task 2) with an ROP of \(-11\) dBm. The optical  
Figure 5: BER vs. transmision distance for (**a**) 50 GBaud PAM4 and (**b**) 100 GBaud PAM4. Figure 6: BER vs. ROP for (**a**) 50 GBaud PAM4 and (**b**) 100 GBaud PAM4. spectra in both cases demonstrate the efficient utilization of bandwidth and the effectiveness of the AOP in maintaining signal integrity at higher data rates. Regarding the implementation of the AOP, mature photonic integrated platforms already exist which can integrate the necessary optical components. Various methods for integrating these components effectively have been documented in the literature, whether utilizing InP [36; 37; 38; 39] or Si [40; 41; 42; 43] technology. According to typical values reported in the literature, specifically for Si platforms, an estimation of the power consumption of the AOP can be provided.