top of page
Writer's pictureLatitude Design Systems

AI Drives Need For Optical Interconnects In Data Centers: A Review

Introduction

The explosive growth of data driven by artificial intelligence (AI) and machine learning (ML) is creating immense pressure on data centers to adopt optical interconnects for higher throughput and lower latency. Optical communication has evolved from long-haul networks to rack-to-rack and chip-to-chip links inside data centers. However, integrating photonics with electronics remains challenging. Innovations in silicon photonics, packaging, and new protocols are helping address these issues as data centers transition from electrical to optical links.

PIC Studio Enables Photonic IC Design Automation

As artificial intelligence proliferates, the need for low latency and high bandwidth interconnects is driving rapid innovation in photonic integrated circuits (PICs). PIC Studio offers a comprehensive design automation platform that empowers PIC design, simulation, and layout. It supports major foundry process design kits (PDKs) and enables co-design of photonic circuits with electronics through co-simulation. The schematic-driven layout, customizable components, and automation features accelerate PIC design cycles.

PIC Studio Design Flow
PIC Studio Design Flow

Key Trends in Data Center Optical Interconnects

  1. Hyperscalers Lead Adoption of Optical Links Hyperscalers like Google, Facebook, and Microsoft have been early adopters of optical technology in their data centers. The uniformity and scale of their infrastructure allows smooth integration of optics. For enterprise data centers, it has been slower due to greater diversity.

  2. Short Copper Links to Multi-kilometer Fiber Links Data center optical links span multiple levels of connectivity, from board-to-board, chip-to-chip, and on-chip. Short electrical links are giving way to optical fiber for rack-to-rack, data hall to data hall, and even inter-datacenter connections up to 40km using coherent optics.

  3. Multi-Mode Fiber Dominates Intra-Data Center Links Multi-mode fiber is widely used inside data centers for its ease of installation, handling, and cost structure compared to single-mode fiber. However, single-mode offers higher bandwidth and distances.

  4. Active Copper Cables Bridge Electrical and Optical Active copper cables that incorporate transceiver technology offer a midpoint between copper and optical for cost and reach tradeoffs. But increasing speeds are diminishing copper's viability.

  5. Optical Transceivers and Co-Packaged Optics Optical transceivers (QSFP, QSFP-DD) have enabled 400Gbps links but face manufacturability limits. Co-packaged optics like Broadcom's 6.4T optical engine aim to consolidate multiple transceivers onto a substrate integrated with switch ASICs.

  6. New Optical Protocols for Ethernet and PCIe While Ethernet remains the dominant data center protocol, new optical physical layers are being developed. PCIe may transition from copper to optical at 32GBps rates slated for PCIe 7.0 around 2025.

  7. Silicon Photonics, Microring Resonators, and Lasers Silicon photonics are replacing copper to provide energy and cost efficiencies. But further integration of lasers and modulators into photonic ICs remains challenging. Startups are developing optical technologies to link silicon electronics and standalone lasers.

The present and future of optical interconnects
(Source: Synopsys)

Design Innovations for Optical ICs

PIC design automation platforms like PIC Studio accelerate the development of complex optical ICs by enabling circuit-layout co-design and foundry-certified PDK support. The roadmap for optics includes more integration of photonics into advanced chip packaging. Heterogeneous integration and wafer-scale packaging will reduce optical interconnect bottlenecks.

electrical-optical co0simulation

Emerging Standards and Technologies

OIF's ELSFP Agreement Enables Co-Packaged Optics The Optical Internetworking Forum's (OIF) External Laser Small Form Factor Pluggable (ELSFP) agreement defines an optical module standard optimized for co-packaged optics. The front-panel design enhances reliability and serviceability.

PLC Optical Engines Consolidate Transceivers Photonic integrated circuits like Broadcom's 6.4T optical engine consolidate multiple optical transceivers onto a shared substrate with switch ASICs. This co-packaging approach addresses manufacturability limits of pluggable modules.

Direct Optical Wiring Offers Flexible Interconnects Direct optical wiring techniques being developed by startups like Lessengers use novel fiber materials that can be solidified during installation. This provides reconfigurable optical links well-suited for high performance computing applications.

Coherent Optics Enable Long-Haul Connectivity Coherent optics modulate and amplify signals using digital signal processing (DSP), allowing low-loss transmission over tens of kilometers for inter-datacenter links.

Optical PCIe and CXL For High-Speed Chip-to-Chip Emerging standards for optical PCIe and CXL will replace copper with optical fibers for low latency chip-to-chip interconnects within servers and racks. Optics become essential above 32Gbps serial rates.

Direct optical wiring
(Source: Lessengers)

The Future of Optical Data Centers

AI and machine learning workloads will continue driving data center innovation in low latency optical interconnects. New packaging, materials, protocols, and design tools are ensuring the industry can keep pace with the exponential growth in data. While hurdles remain in cost-effective volume manufacturing, the economics clearly favor the transition from electrical to optical links.

The next decade will witness data centers built around an all-optical foundation transforming compute and connectivity. As throughput doubles every 12-18 months, only optics can deliver the speed and bandwidth demanded by AI compute clusters. The flexiblity of reconfigurable optical fabrics will enable dynamic topologies tailored to workloads. Colocation providers are already offering up to 100Gbps optical connectivity to hyperscale customers.

True optical data centers will require holistic innovation encompassing materials, devices, packaging, protocols, and design automation. Silicon photonics and integrated lasers promise to dramatically lower costs once volume manufacturing matures. Optical design platforms like PIC Studio will empower rapid development of photonic ICs optimized for data center environments. With so much momentum across the industry, the terabit optical data center is closer than ever to becoming reality.

The exponential growth in data driven by AI is creating a compelling imperative for data centers to adopt optical interconnect technology. Innovations in silicon photonics,packaging, protocols, and design automation platforms like PIC Studio will enable this transformation. Heterogeneous integration of photonics and electronics will be key to overcoming the bottlenecks of electrical data links. While hurdles remain, the economics point towards data centers becoming predominantly optical in the coming years as artificial intelligence workloads necessitate ultra high bandwidth, low latency data transmission.

コメント


bottom of page