Analog feedforward equalizer optimization in the context of 50G-PON

We address one of the challenges of 50 gigabit capable passive optical network (50G-PON) implementation induced by the limited bandwidth of low-cost components and signal distortions of fiber transmission and photonic devices. In the context of the broadband access network, and more specifically 50G-PON, the simplest and most affordable solution is usually the best. Implementing an analog feedforward equalizer (AFFE) is not as simple as using digital feedforward equalizer (DFFE) techniques but is relevant from a cost and energy consumption point of view. AFFE has a number of advantages, such as lower power consumption and lower latency, due to the fact that it avoids using an analog-to-digital converter (ADC). In this work, we focus on AFFE optimization techniques to mitigate intersymbol interference (ISI) and chromatic dispersion (CD) and therefore improve signal quality. We model an AFFE in order to reduce a complex problem (because of AFFE’s inter-cells non-uniformity and intra-cells non-linearity, for example) into a simpler formulation that can be solved according to a minimum mean square error (MMSE) approach. This approach is possible when the transmission channel does not fluctuate. Experimental validation through electrical and optical setups demonstrates the effectiveness of the proposed optimization, achieving a significant reduction in the bit error rate (BER) and opening eye diagrams for better signal clarity, thereby offering a viable solution for future optical networks.