Celestial AI Introduces Photonic Fabric™ Module - World’s First SoC with In-Die Optical Interconnect, Ushering in a New Era of Interconnects

August 29, 2025 -- Celestial AI, the creator of the Photonic Fabric™ scale-up networks for accelerated computing, has introduced the Photonic Fabric Module, the world’s first System-on-Chip (SoC) with optical interconnect integrated in the middle of the silicon die — a groundbreaking achievement in semiconductor SoC design that redefines performance and scalability in AI and high-performance (HPC) computing. Photonic Fabric is a revolutionary optical interconnect technology platform that is thermally stable and can be integrated ANYWHERE including the middle of high TDP ASICs. By freeing up the silicon beachfront and embedding optical IO in the middle of the die, Photonic Fabric shatters the “beachfront” limitations of traditional SoCs. It delivers an exceptionally high bandwidth, low-latency, low-power optical link for XPU- XPU, XPU-Switch & XPU-Memory connectivity.

Photonic Fabric Module:

The Photonic Fabric Module (PFM) is a multi-chip module (MCM) that incorporates an advanced TSMC 5nm ASIC (comprised of an 8 Tbps switch, 2x HBM3e controllers, and 4x DDR5 controllers), a photonic interposer (PIC), 2 HBM3e stacks, and a Fiber Array Unit (FAU) in a 2.5D package with 7.2 Tbps of optical connectivity. The HBM acts as a cache to the DDR5 memory; thus, from a processor’s perspective, it sees the bandwidth of the HBM but the capacity of the DDR5. Up to 16 PFMs can be integrated in a rack-mountable Photonic Fabric Appliance (PFA) connected to 16 AI processors or servers, offering a unified memory address space of up to 32TB. This has key applications in AI workloads for KV Cache offloading and embedding services. In addition, along with the PF-Chiplet (see below), the Photonic Fabric operates as an endpoint scheduled scale-up fabric for XPU-XPU connectivity. The Photonic Fabric technology platform also encompasses advanced software for optical link management, telemetry, RAS and AI based predictive analytics. The Photonic Fabric software stack is modular, designed for integration with hyperscale fleet management systems and supports industry standard APIs and management interfaces.

Photonic Fabric NIC:

The Photonic Fabric Module (PF-NIC) is a multi-chip module (MCM) that incorporates an advanced TSMC 5nm ASIC with PCIe 6 and CXL 3.1 support, a photonic interposer (PIC), and a Fiber Array Unit (FAU) in a 2.5D package with 7.2 Tbps of optical connectivity. The PF-NIC can be plugged into any PCIe socket in a server to enable the processors to talk to the PFA and access up to 32TB of shared high- speed memory at less than 250ns latency. This enables the remote memory appliance to act as virtually local and opens a new exciting range of possibilities in memory system design.

PF-Chiplet

The Photonic Fabric Chiplet (PF-Chiplet) is an optical connectivity chiplet based on industry standard (e.g. UCIe) or proprietary die-to-die interface offering up to 14.4 Tbps of optical connectivity per chiplet to XPU. The chiplets are protocol adaptive (AXI, UAL, proprietary protocols) and compatible with standard packaging flows from multiple OSAT vendors. The chiplets can be used for high bandwidth, low-latency XPU-XPU, XPU-Switch, and XPU-Memory (PFA) links.