Lightspring, a French deeptech venture, has completed a €3.1 million seed funding round spearheaded by Atlantic and OVNI Capital. The round also drew backing from Concept Ventures, Ixcore, Plug and Play Ventures, and several industry business angels. The company has additionally earned recognition as a laureate of i-Lab, France's national deeptech innovation competition.

The startup's focus centres on manufacturing optical interfaces for photonic integrated circuits. Through the application of 3D lithography directly to chips, Lightspring transforms photonic packaging—currently the most costly and least consistent phase of production—into a controlled, repeatable manufacturing process.

AI infrastructure demands optics closer to compute

Each advancement in AI hardware architecture brings optical components nearer to processing units. Co-packaged optics relocates the optical interface from the device faceplate to the substrate, positioning it adjacent to switches or accelerators. This shift, however, relocates the system's most challenging manufacturing hurdle into the package itself.

This assembly step has never reached industrial scale. While photonic integrated circuit fabrication itself relies on a small number of established foundries, the assembly and optical packaging phases represent roughly 50 per cent of a PIC's total cost, compared with approximately 20 per cent for foundry operations.

Coupling fibres to chips remains a labour-intensive task, executed individually through micrometre-level active alignment. This approach typically introduces 2–3 dB of optical loss, delivers limited throughput, produces inconsistent yields, and lacks standardisation.

Consolidating optical fabrication into a single step

Lightspring employs 3D lithography, specifically two-photon polymerisation (2PP), to create optical coupling structures including microlenses, 3D waveguides, and beam-shaping elements directly onto chips.

The single-step process is engineered to deliver:

  • Fibre-to-chip, laser-to-chip, and chiplet-to-chiplet coupling with target coupling losses below 0.5 dB per interface
  • Elimination of precision pre-alignment requirements, removing active alignment entirely
  • An approach independent of specific materials or equipment
  • Design cycles spanning under two weeks, versus several months for conventional optical packaging solutions

Lightspring's principal intellectual property resides in the design layer: the inaugural Process Design Kit (PDK) for 3D optical coupling, combined with software-driven design tools and validated fabrication protocols.

The underlying technology stems from nationally and EU-supported research conducted at the FEMTO-ST Institute in Besançon, a joint research facility operated by CNRS and UMLP with over 700 personnel. The institute ranks among Europe's foremost institutions in optics and micro-nanotechnology. Daniel Brunner, Lightspring's co-founder, holds the position of CNRS Research Director at the institute.

Grégoire Bonnat, co-founder and CEO of Lightspring, stated:

The whole industry is working on making photonic chips faster, yet light still loses most of its energy the moment it enters or leaves the device. We decided to attack that specific problem: to build the optical interface the same way the rest of the chip is built, in one reproducible process step. This funding will turn a lab result into a qualified industrial building block.

Grégoire Bonnat, CEO of Lightspring

Combined with a €350,000 grant and supplementary public innovation funding, Lightspring has now assembled over €3.5 million in both equity and non-equity financing. These resources will enable the transition of its 3D optical coupling process from laboratory research to production-scale manufacturing.

Quentin Calleja, Principal at Atlantic, remarked that photonics adoption within AI infrastructure is accelerating rapidly, yet optical packaging continues to represent a time-consuming and expensive constraint.

Lightspring has developed a technology that finally makes it scalable. We back teams with the potential to become the leaders of categories that don't exist yet, and Lightspring is definitely one of them.

Quentin Calleja, Principal at Atlantic

Thomas Renaudin, Founding Partner at OVNI Capital, emphasised that successive generations of AI hardware push optics progressively closer to compute, with co-packaged optics representing the endpoint of this trajectory.

The industry has the roadmap; what it does not have is a way to manufacture the optical interface at volume. Lightspring is building that layer — from Europe, for a market that is global from day one.

Thomas Renaudin, Founding Partner at OVNI Capital

The funding will support advancement of Lightspring's PDK and design tools, grow its workforce to 12 employees, finance collaborative engineering initiatives with industrial partners, and accelerate the scaling and qualification of its fabrication process for commercial deployment.

Source: Tech.eu