Electro-Optical Integration: TSMC’s COUPE Platform Enhances XPU-to-XPU Connectivity via Optical Interconnection
Original Article By SemiVision Research (TSMC, Nvidia , Lightmatter, Celestial AI, Ayar Labs)
TSMC is positioning Silicon Photonics as a core enabler for the future of optical interconnect technologies. The company is building a comprehensive strategy that spans wafer-level processes, photonic device design, 3D packaging, heterogeneous integration, and system-level platforms. At the heart of this roadmap is the COUPE (Compact Universal Photonic Engine) platform, which serves as a foundational technology for achieving Co-Packaged Optics (CPO) and high-efficiency data transmission architectures.
The paper in focus presents a novel approach to implementing an Optical I/O architecture under Nvidia’s upcoming Feynman platform. It’s not only technically innovative but also represents a deep integration of TSMC’s COUPE technology. For anyone looking to understand Nvidia’s Feynman architecture, this paper is a must-read.
Moreover, readers interested in the broader field of optical computing and interconnects, especially companies like Lightmatter, Celestial AI, and Ayar Labs, should also take note of this work. Notably, TSMC’s paper cites 31 references, underlining its technical depth and relevance.
It also outlines key directions for future silicon photonics development, particularly in the context of next-generation 448G SerDes architectures—making it an essential reference for those following the evolution of high-speed optical interfaces.
At the 2024 IEEE ECTC, TSMC presented a technical paper titled "High Bandwidth and Energy Efficient Electrical-Optical System Integration Using COUPE Technology". The paper provides a systematic explanation of how the COUPE architecture is integrated with SoIC (System-on-Integrated-Chip) technology, addressing the high-bandwidth and low-power demands of Generative AI through comprehensive system-level simulation and electro-optical co-design verification.
TSMC’s silicon photonics strategy has increasingly drawn global attention. Departing from the traditional role of a pure-play foundry, TSMC is actively redefining itself as a heterogeneous systems integrator. Notably, in its 2025 ECTC papers and presentations, TSMC has expanded its focus to include chip-to-chip thermal architectures, power delivery network (PDN) design, and high-frequency interconnects between optical modules, GPUs, and HBM memory—highlighting a growing emphasis on system-level challenges.
This article will focus on the critical circuit-level challenges TSMC faces when integrating Photonic Integrated Circuits (PICs) with Electronic Integrated Circuits (EICs)—a convergence we refer to as the EPIC architecture. Key topics include:
Why TSMC consistently emphasizes the critical role of SoIC in improving circuit performance
How 3D stacking and ultra-short interconnect paths help minimize parasitic capacitance and signal loss
Why PSRR (Power Supply Rejection Ratio) has become central to power integrity and bit-error rate challenges in optical modules
How TSMC utilizes enhanced interposers and high-speed SerDes signaling to connect optical modules with high-performance chips like XPU and HBM
Through this deep-dive analysis, we aim to clarify TSMC’s core strategies and implementation techniques in electro-optical heterogeneous integration (E-O Co-Integration), shedding light on how the company is evolving from a process leader to a full-stack enabler of next-generation AI infrastructure based on photonic-electronic system platforms.
COUPE and the Future of AI Optical-Electrical Integration — Focusing on XPU-to-XPU and Switch-to-XPU Optical Links
As generative AI pushes the boundaries of data scale and model complexity, next-generation system architectures must address unprecedented demands for bandwidth, energy efficiency, and interconnect scalability. Industry leaders like NVIDIA are actively re-architecting AI superchip systems, with the Feynman architecture serving as a prime example of this evolution—designed to support ultra-high-density, low-power interconnects for XPU-to-XPU and Switch-to-XPU communication. In this context, TSMC’s COUPE (Compact Universal Photonic Engine) platform emerges as a foundational technology enabling these transformative interconnect paradigms.
Published at IEEE ECTC 2024, the paper titled “High Bandwidth and Energy Efficient Electrical-Optical System Integration Using COUPE Technology” provides a comprehensive overview of TSMC’s platform-level advancements in optical-electrical co-integration. Beyond packaging innovations, it delves into the electrical design and performance optimization of key optical engine components such as the Transimpedance Amplifier (TIA), Laser Driver, and Photodetector (PD). These components form the backbone of high-speed, low-power optical transceivers necessary for AI chiplet integration.
At its core, COUPE is designed as a SoIC-based photonic engine platform optimized for XPU-to-XPU optical links, leveraging 3D stacking of Electronic ICs (EICs) over Photonic ICs (PICs) through bump-less copper-to-copper bonding. This results in ultra-short interconnects with minimal parasitic effects, supporting lower latency and higher integration density—exactly the architectural direction envisioned by NVIDIA for Feynman-based optical systems. In parallel, COUPE also enables Switch-to-XPU links for Co-Packaged Optics (CPO), offering a seamless electrical-optical interface within next-generation optical switches.
To further enhance system integration, TSMC introduces Enhanced Interposer technology, incorporating multi-layer GSGS/GSSG transmission line structures. This significantly reduces interconnect power consumption and improves signal integrity across XPU-to-OE and XPU-to-MEM interfaces. It creates a scalable interconnect foundation suitable for large-scale AI/HPC systems with multi-die and disaggregated memory architectures.
This article will explore COUPE’s layered architecture—from device-level design and electrical modeling to interposer routing and system-level impact—demonstrating how it addresses the challenges of XPU-to-XPU and Switch-to-XPU optical interconnects in future Zettascale AI platforms.
Is This the Optical Moment? Thought-Provoking Questions from the TSMC–NVIDIA Silicon Photonics Alliance
As generative AI continues its rapid evolution, can traditional electrical interconnects still meet the bandwidth and latency demands of trillion-parameter models?
Why are leading foundries shifting from μ-bump to SoIC-based photonic integration? Could this reflect a deeper transformation in system design philosophy?
What challenges emerge when <5 μm microring modulators are densely integrated into multi-thousand channel optical engines—especially in terms of packaging density and thermal design?
Why does improving TIA receiver sensitivity significantly reduce laser power consumption and system-level cooling costs in AI supernodes?
In architectures integrating DWDM and comb lasers, how must the interposer design evolve to simultaneously support SI/PI integrity, BER reliability, and warpage resilience?
As TSMC builds its COUPE architecture, is it also redefining the principles of packaging-aware photonic co-design? What strategic direction does its System Foundry ambition truly signal?
If optical engines become the backbone of next-generation XPU-to-XPU connectivity, how should packaging respond to the energy and reliability demands of 25 Tbps bandwidth?
With AI computing entering the Zettascale era, will conventional packaging and data center designs face a complete architectural rewrite?
As AI supernodes continue to scale, can TSMC’s COUPE + Enhanced Interposer solution become the industry standard for electro-optical integration?
When μ-bump architectures can no longer support multi-wavelength high-speed transmission, has SoIC become the inevitable foundation for photonic chiplet systems?
For Paid Members, SemiVision will discuss topics on
SoIC-Based Integration with Photonic Engine: Enabling High-Density, Low-Power Heterogeneous Stacking
Transmitter–Receiver Co-Optimization: Full-System Performance Boost through Simulation and Validation
Enhanced Interposer: Enabling Long-Reach, Energy-Efficient Die-to-Die Interconnects
Building a Co-Packaged Optics System Platform: Horizontal Integration from Process to Packaging
The Explosive Growth of Generative AI Models Presents New Challenges for Hardware Architectures
System Bottlenecks of Existing Pluggable Optics Modules
TSMC’s COUPE Technology and Its System-Level Advantages
The Strategic Vision Behind COUPE: Transforming TSMC into a Heterogeneous System Platform Provider
TSMC’s COUPE Architecture: A Foundational Platform for XPU-to-XPU Optical Interconnects
COUPE System Modules and Interconnect Characteristics
WDM Module Integration: Advancing Toward Terabit-Scale Bandwidth
XPU-to-XPU COUPE Link: Stepping Into the 448G SerDes Era
Applications and Future Outlook
TR and RX Circuit Design Concepts: A Deeper Dive
Electrical Simulation and Comparative Analysis (Transmitter and Receiver)
Transmitter Simulation Analysis
Evolution of WDM Channel Count and Microring/Microdisk Dimensions
Why Did TSMC Choose SoIC Technology?
μ-bump vs. SoIC: Microring Modulator Integration and Performance Comparison
μ-bump vs. SoIC: Microring Modulator Integration and Performance Comparison
Future Implications: Co-Design of Packaging and Bandwidth
Enhanced Implications of SoIC Architecture in TIA and Driver Design
TIA and PD: Physical Challenges in the Receiver and the Advantages of SoIC
TIA Sensitivity and Noise Behavior: How SoIC Enhances SNR
Laser Power and System Energy Efficiency: From Packaging Optimization to AI Infrastructure Transformation
The Core Value of SoIC in Driving AI Optical-Electrical Packaging
Enhanced Interposer — Optimizing OE-to-XPU Interfaces
OE-to-XPU Signal Transmission Model
Key Benefits of Enhanced Interposer (Based on 25 Gbps Simulation)
Comprehensive Advantages of the COUPE + Enhanced Interposer Packaging Architecture
Significant Interconnect Efficiency Improvements via the Enhanced Interposer
