## 2 Experimental Setup and Principle of Operation  
The architecture of the proposed BMWC and the experimental setup used for the evaluation of its operation are illustrated in Figure 1. The BMWC utilizes a differentially-biased SOA-MZI, where the two SOAs are operated in a deeply gain saturation regime, to realize a non-linear transfer function with clipping properties [21; 31]. More specifically, at the steady state conditions, one of the two SOAs is deeply saturated in the transparency region, i.e., allowing all of the signal to simply pass through its waveguide structure without any amplification, while the second SOA is operated in a slightly less saturated condition with some small gain-amplification and before the transparency region. This saturated differential biasing condition allows setting the steady-state gain levels of two SOAs in an asymmetrically biased condition that corresponds to a constant differential phase shift close to \(\pi\) between its two branches, when no other control data signal is present. When a control signal is injected into the device, it leads both SOAs performing close to their gain transparency region, as such the SOAs\({}^{\prime}\) carrier fluctuation and intensity modulation are greatly reduced, supporting clipping properties and strongly power equalized output pulses. On the other hand, when SOAs are operated in a symmetrically biased condition, as in simple WC or push-pull schemes [33], they are generating amplitude fluctuations, jitter and transient phenomena as described in more details in [34].  
In order to achieve these operational conditions, the two SOAs of the BMWC are each powered by a Continuous Wave (CW), gain-clamping, assist-light beam at \(\lambda\)as\({}_{1}\) = \(\lambda\)as\({}_{2}\) = 1548 nm and a power level of 7.13 dBm and -11.93 dBm, through SOA-MZI ports D and E, respectively. The present optical power levels enable gain clamping of the two SOAs in the saturated regime, where faster SOA gain dynamics are observed, while also setting a differential biasing with a constant \(\pi\) differential phase shift. In order to perform the wavelength conversion, a data signal on a \(\lambda_{1}\) wavelength of 1550.4 nm was injected into two cascaded LiNbO\({}_{3}\) modulators, that were driven by Programmable Pattern Generators (PPGs). The first PPG was used to produce two sequential 10 Gb/s or 20 Gb/s \({}^{2}\)\({}^{\prime}\)\(-\)1 Pseudo Random Bit Sequences (PRBS) packets, while the second modulator was used to apply different optical power levels to the packets by changing its driver's gain. The present transmission setup allows emulating the bursty packet traffic generated through two different users with arbitrarily varying power levels, stemming from various near or far distant locations of the converged access-network.  
After generating the data packets, the data signal was amplified by an Erbium Doped Fiber Amplifier (EDFA) and filtered by a 3 nm Optical Bandpass Filter (OBPF), and then split into two identical signals through a 50:50 coupler before reaching the BMVC device. The two signals were then bit-level synchronized through an Optical Delay Line (ODL), so as to be simultaneously injected at the two available control ports A and H of the SOA-MZI and act as control signals of an optical push-pull configuration. This allows performing Cross-Phase Modulation (XPM) switching phenomena simultaneously at both branches of the SOA-MZI, facilitating fast response and gain recovery dynamics with almost constant differential phase shift between the two branches during the transient gain recovery immediately after a control pulse is extinct. A CW beam at \(\lambda_{2}\) = 1549.3 nm was injected as input into the BMWC through port B, with its power level measured at 6.96 dBm. The two control signals featured power levels of 9.8 dBm and \(-\)1.5 dBm respectively, while the SOAs were driven at 268 mA and 330 mA, respectively.