# The Multiband over Spatial Division Multiplexing Sliceable Transceiver for Future Optical Networks
## 6 Experimental Assessment
### MBoSDM Transmission Assessment  
A second experimental assessment is performed for the MBoSDM transmission, as a key scenario to provide the required capacity scaling expected in future networks. Hence, a 19-cores MCF of 25.4 km is considered in the setup of Figure 5 to evaluate the performance of the proposed MB(oSDM) S-BVT. The total optical power of the C-, L-, and S-bands optical signals launched into the MCF fibre, measured in the optical spectrum analyser (OSA), is \(-1.6\) dBm. In this particular scenario, the estimated SNR profile per subcarrier is depicted in Figure 10a, showing the CD impact on the DSB L-band contribution. Specifically, the first attenuation peak due to CD appears at 10.9 GHz corresponding to a CD coefficient of 19.4 ps/(nmkm) at 1600 nm, according to Equation (4). Additionally, a degradation in terms of SNR is shown when comparing with the SSMF path of 25 km, depicted in Figure 8d. In fact, for this particular length the MCF presents higher attenuation values per core, of up to 10 dB (measured within the C-band), with respect to the 5 dB attenuation within the SSMF. A first assessment is performed without considering the XT. In this particular case, the achieved capacity per band after transmitting over the MCF is shown in Figure 10b. From the figure, it can be seen that the C-band contribution achieves the highest data rate of 44 Gb/s at the target BER and 36 dB optical signal noise ratio (OSNR). A capacity of 35.8 Gb/s (L-band) and 39.3 Gb/s (S-band) is obtained at 37.8 dB OSNR and 31.7 dB OSNR, respectively. In fact, when transmitting across the MCF, different performance per band is expected due to the wavelength dependence of fibre properties, such as effective area, CD and fibre attenuation/loss. Thanks to the exploitation of SDM, spatial dimension can be also considered and new resources are available to further scale overall network capacity. A full population of the S+C+L-bands with a single core of the 19-cores MCF will envision data rates of 13.8 Tb/s for the S-band (350 channels), 7.7 Tb/s for the C-band (175 channels) and 5.5 Tb/s for the L-band (150 channels). Hence, considering S+C+L bands and the 19 cores, the aggregated capacity can scale up to 500 Tb/s (19\(x\)27 Tb/s). Figure 9: Achieved maximum data rate and OSNR per slice considering different fibre paths of up to 75 km length. Out-Band and In-Band XT Evaluation  
Here, the out-band and in-band XT are evaluated using the data generation module of Figure 5, which feeds the adjacent cores (\(\#2,3,4,5,6\), and 7) of the MCF. In particular, for the out-band XT assessment, the data generation module consists of the S-band amplified contribution after the MCF. The S-band amplifier (TDFA-based) pump laser diode (LD) current is varied in steps of 100 mA up to a maximum value of 500 mA, to evaluate the impact of the out-band XT within the C-band and L-band. However, similar capacity of about 38 Gb/s is obtained in all the analysed cases, as the OSNR slightly varies around 34 dB. This translates to 6 Gb/s data rate decrease in comparison with the scenario that not considers XT, where 44 Gb/s was achieved at 35 dB OSNR. In the case of L-band, the same data rate of 35.8 Gb/s is achieved at the target BER, and 37.8 dB OSNR with and without out-band XT, as the selected S-band and L-band wavelengths are 100 nm separated. Finally, the in-band XT within the C-band is evaluated. In this scenario, the data generation module of Figure 5 is based on a C-band broadband source (BS) and an EDFA. The power profile before and after amplification is shown in Figure 11. We have varied the output power of the EDFA in order to vary the impact of the in-band XT. As a result, the achieved data rate versus OSNR is depicted in Figure 12. From the figure, it can be seen that a maximum data rate of 44 Gb/s (point A) is achieved without XT at 35 dB OSNR and the target BER. The data rate of the C-band contribution decreases with the increasing of the in-band XT signal power down to 22 Gb/s (point B) at 23.6 dB OSNR.