# The Multiband over Spatial Division Multiplexing Sliceable Transceiver for Future Optical Networks
## 7 Conclusions and Future Directions  
A modular and scalable MB(oSDM) S-BVT is proposed as a key element to provide suitable capacity scaling to meet the demands of future optical networks. A proof-of  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Component** & **MB(oSDM) S-BVT DD** \\ \hline MZM & 3 \\ Driver & 3 \\ DAC & 3 ports \\ ADC & 3 ports \\ (Laser source) \(LS_{S}\) & 1 \\ \(LS_{C}\) & 1 \\ \(LS_{L}\) & 1 \\ \(WSS_{TxS}\) & 1 port \\ \(WSS_{TxC}\) & 1 port \\ \(WSS_{TxL}\) & 1 port \\ \(WSS_{RS}\) & 1 port \\ \(WSS_{RxC}\) & 1 port \\ \(WSS_{RxL}\) & 1 port \\ \(BPT_{Tx}\) & 3 outputs \\ \(BPF_{Rx}\) & 3 outputs \\ Photodetector (PD) & 3 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Number of elements for a MB(oSDM) S-BVT with DD.  
concept of the proposed transceiver based on DD and adaptive OFDM, considering 3 slices working within the S-, C-, and L-bands, is experimentally assessed. MB and MBoSDM transmission is demonstrated over a SSMF path of 75 km and a 19-cores MCF of 25.4 km length. Aggregated capacities of 212 Gb/s and 119 Gb/s are achieved ensuring the target BER in a B2B configuration and after the 25.4 km MCF path, respectively. Thanks to the scalable transceiver architecture and the exploitation of MB and SDM technologies, 500 Tb/s per fibre transmission can be envisioned with the full population of the three analysed bands and the 19 cores of the MCF. The impact of XT in the transmission is numerically and experimentally evaluated, highlighting the importance of managing signal power levels feed into the different cores of the MCF system. Additionally, a complexity/cost analysis of the proposed transceiver solution has been included analysing the impact of enabling MB technology. The presented preliminary assessment of the proposed transceiver shows the benefits and advantages of MBoSDM as key strategy to be adopted in future optical networks towards supporting the expected traffic demand and stringent requirements. On this regard, the investigation of additional spectral bands beyond S+C+L bands and related transmission impairments will be crucial to analyse the capabilities of the technology/solution. Finally, the interaction and integration of the proposed transceiver in a MBoSDM network is also a challenge to be addressed to validate the full potential of the proposed approach.  
Conceptualization, L.N., J.M.F. and M.S.M.; methodology, L.N., J.M.F. and M.S.M.; software, L.N. and J.M.F; validation, L.N., M.A. and F.J.V.; investigation, L.N., J.M.F. and M.S.M.; resources, L.N.; data curation, L.N.; writing--original draft preparation, L.N.; writing--review and editing, L.N., J.M.F., M.A., F.J.V. and M.S.M.; visualization, F.J.V.; supervision, L.N. All authors have read and agreed to the published version of the manuscript.  
This work has been partially funded by the projects EU SEASON (101096120), EU and I-CERCA CERCAGINYS with the support of the Spanish Ministry of Science and Innovation, the Spanish RELAMPAGO grant (PID2021-127916 OB-I00) funded by MCIN/AEI/10.13039/501100011033/FEDER, UE and UNICO-5G programme 6G-OPTRAN grant (TSI-063000-2021-22/23/115) funded by \"Ministerio de Asuntos Economics y Transformacion Digital\" and the European Union-NextGenerationEU in the framework of the \"Plan de Recuperacion, Transformacion y Resiliencia\" and of the \"Mecanismo de Recuperacion y Resiliencia\".  
Data sharing not applicable.  
The authors declare no conflict of interest.