Silicon Photonics Poised to Smash AI Data Bottlenecks

2026-10-28 semicon

Leuven, Wednesday 28 October 2026
Imec’s integrated optical interconnects bypass copper’s physical limits, targeting a dramatic energy drop to two picojoules per bit to power next-generation artificial intelligence data centres efficiently.

The Physical Limits of Copper in Hyperscale Architectures

The rapid ascent of generative, reasoning, and agentic artificial intelligence platforms has created an unsustainable burden on hyperscale computing infrastructure [1]. At the core of this challenge lies a physical impasse: traditional copper interconnects are running out of headroom [1]. As data transmission rates surge, electrical signalling experiences aggressive high-frequency attenuation, severe thermal bottlenecks, crosstalk, and degraded signal integrity over distances longer than a few millimetres [1]. Contemporary 800G DR8 transceiver modules require roughly 13 watts of power, translating to a steep energy expenditure of 16 pJ/bit [6]. With leading hyperscale operators responsible for 60% of top-tier accelerator demand [3], system designers face the stark reality that standard copper interfaces cannot scale to meet the next wave of cluster training and low-latency inference workloads without consuming an unacceptable share of a data centre’s total energy budget [1][3].

Industrial Scaling and the Imec Photonics Blueprint

The financial incentives driving the transition towards optical alternatives are substantial [3]. By March 2026, Nvidia’s compute order backlog climbed from $500 million in 2025 to $1 trillion, representing an extraordinary expansion of 199900% [3]. Concurrently, frontier labs Anthropic and OpenAI scaled to annualised revenue run rates of $25 billion each by April 2026, reinforcing the urgency of resolving inter-accelerator communication bottlenecks [3]. To support this volume, research hubs and foundries are overhauling transceiver technology [1][5]. While first-generation 1.6T pluggable transceivers using 200 Gbps per lane are entering sampling and initial deployment, the wider sector is preparing for 3.2T interfaces by 2030, which require optical modulators capable of exceeding 100 GHz operating bandwidths [1]. Extreme pluggable optics (XPO) architectures are also on product roadmaps, aiming to deliver capacities of up to 12.8T through liquid cooling and denser integration [1].

Engineering Breakthroughs: From Lithium Tantalate to Barium Titanate

In Leuven, imec is addressing these scaling walls through its pre-competitive Optical Interconnect Program, directed by Peter Ossieur, which targets scaling engine bandwidth from 1.6T and 3.2T up to 6.4T and 12.8T [1]. Drawing upon more than two decades of research on a mature 300 mm CMOS-compatible silicon photonics platform, the hub divides its development into OI-EXPLORE (technology pathfinding up to TRL 3) and OI-DEMO (prototyping across TRL 3 to 5) [1][2]. imec has achieved notable material milestones, including the seamless integration of thin-film lithium niobate (LiNbO₃) and the first heterogeneous integration of lithium tantalate (LiTaO₃) modulators onto silicon photonic integrated circuits via micro-transfer printing [1]. Together with Ghent University researchers, imec demonstrated an unamplified O-band 320 Gbps link across 2 km of single-mode fibre using a 100 GHz germanium photodiode [1]. Furthermore, in October 2025, imec announced a GeSi electro-absorption modulator (EAM) leveraging the Franz-Keldysh effect, operating past 110 GHz in the C-band at 400 Gbps per lane [1].

Co-Packaged Optics: Eradicating the DSP Penalty

Beyond individual modulators, the industry’s architectural transition hinges on co-packaged optics (CPO), which mounts optical engines within millimetres of the compute silicon or switch die [1]. By shortening the electrical distance, CPO eliminates the power-hungry digital signal processor (DSP) required by standard front-panel pluggables, cutting optical transceiver subsystem power substantially [1][6]. Deployments of initial CPO architectures demonstrate marked gains: while early cascaded Mach-Zehnder modulator engines consumed 5.5 pJ/bit—or 11 pJ/bit including the external continuous-wave laser—Intel demonstrated integrated laser configurations running at 3 pJ/bit, and imec demonstrated micro-ring modulator architectures at 4 pJ/bit [6]. Imec’s advanced 2.5D optical I/O framework (OIO2.5D) targets optical engines delivering 8 to 32 Tbps aggregate bandwidth with lane rates of 32 to 64 Gbps, a bandwidth density of 2 Tbps/mm, and an energy target of ~2 pJ/bit, down from broader historical footprints of 5 pJ/bit [1]. Long-term 3D integrated optics (OIO3D) aim for similar 2 pJ/bit levels before trending into sub-pJ/bit domains [1].

European Strategic Autonomy and Ecosystem Synergy

Commercialisation roadmaps point towards widespread hyperscale adoption of co-packaged optics from 2027 to 2028, with Nvidia scheduling Feynman NVLink 8 CPO switches for release in 2028 [1][3]. Proof-of-concept units for vertical 3D optical integration are expected between 2029 and 2031, ahead of full industrial volume manufacturing anticipated between 2031 and 2036 [1]. Parallel to transceiver redesigns, optical circuit switching (OCS) is restructuring cluster fabrics; Google’s OCS implementations have lowered switching power by 40%, generating a market opportunity projected by CignalAI to exceed $3 billion, with European innovators such as iPronics and Salience Labs demonstrating high-radix fabrics [3]. Within Europe’s semiconductor landscape, imec’s 300 mm packaging advances—incorporating copper hybrid bonding with pitches down to 400 nm and barium titanate processes developed alongside Veeco Instruments in January 2026—mesh closely with equipment leaders such as ASML and pure-play foundry platforms like X-FAB [1][2][5][7]. Together with academic institutions like Ghent University, where pioneer Roel Baets helped build the region’s photonic foundation, this integrated ecosystem provides Europe with proprietary intellectual property, industrial resilience, and technological sovereignty as artificial intelligence hardware enters the multi-terabit optical era [1][2][4][5][7].

Sources & Ecosystem Partners

Silicon photonics Optical interconnects