Multiplexing in photonics as a resource for optical ternary content-addressable memory functionality

In this paper, we combine a Content-Addressable Memory (CAM) encoding scheme previously proposed for analog electronic CAMs (E-CAMs) with optical multiplexing techniques to create two new photonic CAM architectures-wavelength-division multiplexing (WDM) optical ternary CAM (O-TCAM) and time-division multiplexing (TDM) O-TCAM. As an example, we show how these two O-TCAM schemes can be implemented by performing minor modifications in microring-based silicon photonic (SiPh) circuits originally optimized for exascale interconnects. Here, our SiPh O-TCAM designs include not only the actual search engine, but also the transmitter circuits. For the first time, we experimentally demonstrate O-TCAM functionality in SiPh up to similar to 4 Gbps and we prove in simulation feasibility for speeds up to 10 Gbps, 10 times faster than typical E-TCAMs at the expense of higher energy consumption per symbol of our O-TCAM Search Engine circuits than the corresponding E-TCAMs. Finally, we identify which hardware and architecture modifications are required to improve the O-CAM's energy efficiency towards the level of E-CAMs.

Automated summary

This paper introduces the combination of CAM encoding scheme and optical multiplexing techniques to create new photonic CAM architectures. By making minor modifications to silicon photonic circuits, O-TCAM functionality is achieved and its high-speed transmission feasibility is demonstrated. However, O-TCAM consumes higher energy compared to traditional E-TCAM and further optimization is needed.