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Abstract Multi‐socket server boards (MSBs) exploit the interconnection of multiple processor chips towards forming powerful cache coherent systems, with the interconnect technology comprising a key element in boosting processing performance. Here, we present an overview of the current electrical interconnects for MSBs, outlining the main challenges currently faced. We propose the use of silicon photonics (SiPho) towards advancing interconnect throughput, socket connectivity and energy efficiency in MSB layouts, enabling a flat‐topology wavelength division multiplexing (WDM)‐based point‐to‐point (p2p) optical MSB interconnect scheme. We demonstrate WDM SiPho transceivers (TxRxs) co‐assembled with their electronic circuits for up to 50 Gb/s line rate and 400 Gb/s aggregate data transmission and SiPho arrayed waveguide grating routers that can offer collision‐less time of flight connectivity for up to 16 nodes. The capacity can scale to 2.8 Gb/s for an eight‐socket MSB, when line rate scales to 50 Gb/s, yielding up to 69% energy reduction compared with the QuickPath Interconnect and highlighting the feasibility of single‐hop p2p interconnects in MSB systems with >4 sockets.

Analog fronthauling is currently promoted as a bandwidth and energy-efficient solution that can meet the requirements of the Fifth Generation (5G) vision for low latency, high data rates and energy efficiency. In this paper, we propose an analog optical fronthaul 5G architecture, fully aligned with the emerging Centralized-Radio Access Network (C-RAN) concept. The proposed architecture exploits the wavelength division multiplexing (WDM) technique and multicarrier intermediate-frequency-over-fiber (IFoF) signal generation per wavelength in order to satisfy the demanding needs of hotspot areas. Particularly, the fronthaul link employs photonic integrated circuit (PIC)-based WDM optical transmitters (Txs) at the baseband unit (BBU), while novel reconfigurable optical add-drop multiplexers (ROADMs) cascaded in an optical bus are used at the remote radio head (RRH) site, to facilitate reconfigurable wavelength switching functionalities up to 4 wavelengths. An aggregate capacity of 96 Gb/s has been reported by exploiting two WDM links carrying multi-IF band orthogonal frequency division multiplexing (OFDM) signals at a baud rate of 0.5 Gbd with sub-carrier (SC) modulation of 64-QAM. All signals exhibited error vector magnitude (EVM) values within the acceptable 3rd Generation Partnership Project (3GPP) limits of 8%. The longest reach to place the BBU away from the hotspot was also investigated, revealing acceptable EVM performance for fiber lengths up to 4.8 km.