Coherent Comb for Co-Packaged Optics

Project Information

COCOPOP

Grant agreement ID: 101159210

DOI

10.3030/101159210

EC signature date 21 February 2024

Start date 1 April 2024

End date 31 March 2027

Funded under

• The European Innovation Council (EIC)

Total cost

€ 2 482 500,00

EU contribution

€ 2 482 500,00

Coordinated by

PILOT PHOTONICS LTD
Ireland

Periodic Reporting for period 1 - COCOPOP (Coherent Comb for Co-Packaged Optics)

Reporting period: 2024-04-01 to 2025-03-31

Summary of the context and overall objectives of the project

The rise of artificial intelligence (AI), machine learning (ML), and high-performance computing is driving explosive growth in global data traffic. As a result, data centres—particularly those run by hyperscalers—are under pressure to scale their networks efficiently, reduce power consumption, and maintain high performance. Existing optical interconnect technologies, such as co-packaged optics (CPO) and optical I/O (OIO), have emerged to address signal integrity and faceplate limitations. However, these systems are already approaching key limits in fibre count and wavelength density, limiting future scalability.
The COCOPOP project, funded under the European Union’s Horizon Europe EIC Transition programme, is developing a breakthrough solution: the first coherent-capable External Laser Source (ELS) based on chip-scale optical frequency comb technology. This innovation introduces a new dimension for scaling—data rate per wavelength—by enabling coherent communication inside the datacentre for the first time.
COCOPOP aims to deliver a high-performance comb-based ELS product that integrates into today’s IM/DD-based systems and future-proofs them for a seamless transition to coherent optics. Compared to current commercial solutions, the COCOPOP ELS offers:
•  Up to 8× more wavelengths, enabling denser channel packing
•  10–100× narrower linewidths, for better signal fidelity and lower error rates
• 6–10× greater throughput, helping data centres meet escalating traffic demands
• Potential 2× improvements in energy efficiency
At the core of the system is a Silicon Nitride (SiN) chip-scale frequency comb, integrated with a patented injection-locked demultiplexer laser array. This unique combination enables the generation of highly stable, low-noise, phase-correlated wavelengths essential for coherent transmission. The result is a compact, scalable light source that delivers performance well beyond the state of the art.
By achieving TRL7, COCOPOP will deliver a market-ready ELS module aligned with evolving industry standards. Led by Pilot Photonics, the project is positioning Europe at the forefront of datacentre innovation. Project updates and resources are available at https://cocopop.pilotphotonics.com.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the first reporting period, significant technical progress was made towards this goal. Activities focused on validating fundamental building blocks, initiating integration, and developing key subsystems for packaging and control.
Milestone 1 – Comb-Based ELS Lab Demonstration – Achieved
This milestone demonstrated a 100 GHz SiN micro-ring frequency comb, using both passive and active (injection-locked) filtering. The injection-locked approach showed a ~10 dB improvement in output power and ~15 dB improvement in RIN, enabling high-fidelity transmission without external amplification. Data transmission experiments confirmed a 3× throughput improvement, with successful 160 Gbit/s PAM4 transmission.
Milestone 2 – Breadboard Prototype Validation – Partially Achieved
To mitigate delays in PIC fabrication, breadboard development was split into two tracks: a micro-comb breadboard for comb generation and stabilisation, and a laser array breadboard acting as both active demultiplexer and standalone ELS. The micro-comb achieved stable soliton comb generation in a packaged SiN PIC with integrated control. The laser array breadboard, providing 16 channels at >15 dBm output and sub-150 dBc/Hz RIN, now serves as a standalone product in Pilot Photonics’ portfolio. Integration of both subsystems is ongoing.
Milestone 3 – ELS Pluggable Design & Closed-Loop Control – In Progress
Design work progressed with two MPW runs: one for SiN comb PICs and one for the InP demux PIC. Despite some gain alignment issues in the demux PIC, partial compliance was demonstrated and a new tape-out is underway. An OIF-ELSFP-compliant housing has been sourced, and integration design is in progress. Simulations and lab tests validated a promising feedback mechanism for closed-loop control during injection locking.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

COCOPOP’s coherent-capable ELS introduces a third scaling dimension—data rate per wavelength—addressing the growing limitations in fibre and wavelength count in current CPO and OIO systems.
A standout result to date is the development of a 16-channel InP demux PIC and breadboard, aligned to the CW-WDM MSA O-band grid. Designed as part of the comb-ELS, it also functions as a standalone ELS, adding commercial value. Now included in Pilot’s product portfolio, it supports early customer engagement while de-risking the full system integration. The development builds on successful micro-comb demonstrations and injection locking, delivering 3× throughput over passive filtering and validating the comb-based architecture as a viable, high-performance alternative to multi-laser arrays.
To fully realise the project’s impact and ensure its long-term success, the following priorities have been identified:
• Continued system integration and real-world demonstration, particularly the full pluggable ELS prototype at TRL7
• Customer trials and technical validation
• Ongoing IP protection, with three patents already filed, one licensed, and another in preparation
• Standards and ecosystem engagement. Pilot Photonics joined the CW-WDM MSA, which has brought early visibility and alignment with industry specifications