Lightspring, a Besançon-based DeepTech startup that designs and manufactures the optical interfaces of photonic integrated circuits, today announced the close of a €3.1 million Seed round to tackle optical packaging, which today accounts for half the cost of a photonic chip.
The round was led by Atlantic and OVNI Capital, with participation from Concept Ventures, Ixcore, Plug and Play Ventures and industry business angels. The company has also been named a laureate of i-Lab, France’s national DeepTech innovation competition, and has secured a €350k grant. Together with this grant, the Seed round, and additional public innovation funding, the company has secured over €3.5 million in dilutive and non-dilutive financing to move its 3D optical coupling process from lab to production line.
“Photonics is scaling into AI infrastructure fast, but optical packaging remains a slow and expensive step. 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,” said Quentin Calleja, Principal, Atlantic.
Founded in 2026 in Besançon, France, by Grégoire Bonnat, Adrià Grabulosa and Daniel Brunner, Lightspring is building the first 3D-fabricated photonic integration platform.
The company states that by applying 3D lithography directly onto the chip, it turns photonic packaging into a programmable manufacturing step. According to Lightspring, photonic packaging is currently the most expensive and least reproducible step in the chain.
“Every generation of AI infrastructure pushes optics closer to compute. Co-packaged optics moves the optical interface off the faceplate and onto the substrate, next to the switch or the accelerator — and in doing so moves the hardest manufacturing problem in the system into the package itself. That step never industrialised,” Lightspring mentioned in the press release
It notes that while photonic integrated circuit (PIC) fabrication is now handled by a handful of mature foundries, assembly and optical packaging alone account for roughly 50% of a PIC’s cost, compared with around 20% for the foundry step.
It further notes that fibre-to-chip coupling is still performed part by part via micrometre-scale active alignment. A process that brings 2–3 dB of typical optical loss, low throughput, degraded yield and no standard.
Lightspring claims to use 3D lithography (two-photon polymerisation, 2PP) to fabricate optical coupling structures, such as microlenses, 3D waveguides, and beam-shaping elements, directly on the chip.
It’s a single process step that delivers fibre-to-chip, laser-to-chip and chiplet-to-chiplet coupling, with target coupling losses below 0.5 dB per interface. There’s no need for precision pre-alignment, which eliminates the need for active alignment entirely. The company also highlighted that this approach is materials-agnostic and equipment-agnostic, and can complete design cycles in under two weeks, compared with several months for bespoke optical packaging.
“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,” said Bonnat, co-founder and CEO of Lightspring.
Lightspring’s core intellectual property lies primarily in the design layer: the first Process Design Kit (PDK) dedicated to 3D optical coupling, paired with software-driven design tools and qualified fabrication recipes.
According to the French startup, the technology originates from nationally and EU-funded research at the FEMTO-ST Institute in Besançon, a CNRS-UMLP joint research unit of over 700 staff and one of Europe’s leading centres in optics and micro-nanotechnology. Lightspring co-founder Daniel Brunner serves as CNRS Research Director at FEMTO-ST.
“The industry has no standard way to get light into a package, which is why every design is bespoke and every yield number disappoints. We are building one: a PDK for 3D optical coupling that works across foundry platforms and material systems, so designers can adopt it without rebuilding their line. That is what turns a process into a layer the industry can build on,” said Grabulosa, co-founder and CTO of Lightspring.
The company plans to use this capital to develop the PDK and design tools available to PIC designers, and to hire in microfabrication, optical characterisation, and photonic circuit design, bringing the team to 12 people.
It also aims to co-design programmes with industrial partners, focusing on a co-packaged optics roadmap for AI infrastructure, and to scale the fabrication platform and qualify the process under industrial conditions.
