Optical Random Access Memories (RAMs) have been conceived as high-bandwidth alternatives of their electronic counterparts, raising expectations for ultra-fast operation that can resolve the ns-long electronic RAM access bottleneck. In addition, with electronic Address Look-Up tables operating still at speeds of only up to 1 GHz, the constant increase in optical switch i/o data rates will yield severe latency and energy overhead during forwarding operations. In this invited paper, we present an overview of our recent research, introducing an all-optical RAM cell that performs both Write and Read functionalities at 10Gb/s, reporting on a 100% speed increase compared to state-of-the-art optical/electrical RAM demonstrations. Moreover, we present an all-optical Ternary-CAM cell that operates again at 10 Gb/s, doubling the speed of the fastest optical/electrical CAMs so far. To achieve this, we utilized a monolithically integrated InP optical Flip-Flop and a Semiconductor Optical Amplifier-Mach-Zehnder Interferometer (SOA-MZI) operating as an Access Gate to the RAM, and as an XOR gate to the T-CAM. These two demonstrations pave the way towards the vision of integrated photonic look-up memory architectures in order to relieve the memory bottlenecks.
The 5G-induced paradigm shift from traditional macro-cell networks towards ultra-dense deployment of small cells, imposes stringent bandwidth and latency requirements in the underlying network infrastructure. While state of the art TDM-PON e.g. 10G-EPON, have already transformed the fronthaul networks from circuit switched point-to-point links into packet based architectures of shared point-to-multipoint links, the 5G Ethernet-based fronthaul brings new requirements in terms of latency for an inherently bursty traffic. This is expected to promote the deployment of a whole new class of optical devices that can perform with burst-mode traffic while realizing routing functionalities at a low-latency and energy envelope, avoiding in this way the latency burden associated with a complete optoelectronic Ethernet routing process and acting as a fast optical gateway for ultra-low latency requiring signals. Wavelength conversion can offer a reliable option for ultra-fast routing in access and fronthaul networks, provided, however, that it can at the same time offer both packet power-level equalization to account for differences in optical path losses and comply with the typical, in optical fronthauling, NRZ format. In this paper, we demonstrate an optical Burst-Mode Wavelength Converter using a Differentially-Biased SOA-MZI that operates in the deeply saturated regime to provide optical output power equalization for different input signal powers. The device has been experimentally validated for 10Gb/s NRZ optical packets, providing error-free operation for an input packet peak-power dynamic range of more than 9dB.