At the 2024 Optical Fiber Communication Conference, Intel showcased its first fully integrated optical compute interconnect (OCI) chiplet design. Co-packaged with a CPU, it can process real-time data at high speeds, improving the efficiency of high-bandwidth data interconnects in data centers and high-performance computing.
Thomas Liljeberg, senior director of product management strategy at Intel's Integrated Photonics Solutions (IPS), said that the increasing frequency of data transmission between servers is placing tremendous pressure on data center infrastructure, and current solutions on the market are rapidly approaching the practical limits of electrical I/O performance.
Intel's breakthrough development enables customers to seamlessly integrate co-packaged silicon photonics interconnect solutions into next-generation computing systems. Intel's OCI chiplets increase bandwidth, reduce power consumption, and extend transmission distance, accelerating machine learning workloads and revolutionizing high-performance AI infrastructure.
Intel's first OCI chiplet supports 100 channels of 64Gbps data transmission over optical fibers up to 32 meters long, meeting the high-bandwidth, low-power, and long-distance transmission requirements of artificial intelligence infrastructure. This technology also helps enable the scalability of future CPU/GPU cluster connections and new computing architectures, including consistent memory expansion and resource structures, while also accelerating computing efficiency.
Compared to previous I/O connection designs built with materials such as copper wire, although they can support high bandwidth density and low power operation, the transmission distance can only be controlled within approximately 1 meter. Pluggable optical transceiver modules used in data centers and early AI clusters can increase the effective transmission distance, but also increase costs and power loss, making it difficult to expand artificial intelligence workloads.
Intel has proposed an optical I/O solution that can be co-installed with CPUs and other computing components. This solution can support higher bandwidth, reduce energy consumption, lower latency, and increase effective transmission distance, thereby meeting the current expansion needs of artificial intelligence and machine learning computing facilities.
The fully integrated OCI chiplet utilizes Intel's field-proven silicon photonics technology and integrates a silicon photonic integrated circuit (PIC) containing on-chip lasers and optical amplifiers with a circuit chip.
This OCI technology supports up to 4 Tbps bidirectional data transmission and is compatible with PCIe 5.0. This demonstration also established a connection between the transmitter (Tx) and receiver (Rx) between two CPU platforms via a single-mode fiber (SMF) patch cable.
Current small chips can utilize eight pairs of optical fibers, each carrying eight dense wavelength division multiplexing (DWDM) wavelengths, and support 8 channels of 8 Gbps data transmission over distances up to 64 meters (actual transmission distance may be limited to tens of meters due to time-of-flight latency).
This co-packaged solution is also highly energy efficient, consuming only 5 picojoules (pJ) per bit, a significant reduction compared to the approximately 15 pJ per bit consumed by traditional pluggable optical transceiver modules.
Intel's current OCI chiplet is still a prototype product, and it is working with specific customers to design the OCI chiplet and co-package it with their SoC as an optical I/O solution.
