Lightspring raises €3.5M to tackle photonic chip manufacturing bottleneck

French company Lightspring today announced the close of a €3.1 million seed round led by Atlantic and OVNI Capital, with participation from Concept Ventures, Ixcore, Plug and Play Ventures, and industry business angels.

The company also announced it has been named a laureate of i-Lab, France's national deeptech innovation competition. 

Lightspring designs and manufactures the optical interfaces of photonic integrated circuits. By applying 3D lithography directly onto the chip, the company turns photonic packaging — today the most expensive and least reproducible step in the chain — into a programmable manufacturing step.

AI moved optics into the package. Packaging was not ready.

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. While photonic integrated circuit (PIC) fabrication itself is now handled by a handful of mature foundries, assembly and optical packaging alone account for roughly 50 per cent of a PIC's cost, against around 20 per cent for the foundry step.

Fibre-to-chip coupling is still done part by part, through micrometre-scale active alignment — a process that brings 2–3 dB of typical optical loss, low throughput, degraded yield, and no standard.

Building the optics where they belong, in a single step

Lightspring uses 3D lithography (two-photon polymerisation, or 2PP) to fabricate optical coupling structures such as microlenses, 3D waveguides, and beam-shaping elements directly on the chip.

A single process step is designed to deliver:

• Fibre-to-chip, laser-to-chip, and chiplet-to-chiplet coupling, with target coupling losses below 0.5 dB per interface.
• No need for precision pre-alignment, eliminating active alignment entirely.
• A materials-agnostic and equipment-agnostic approach.
• Design cycles under two weeks, compared with several months for bespoke optical packaging.

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.

The technology originates from nationally and EU-funded research at the FEMTO-ST Institute in Besançon, a CNRS-UMLP joint research unit of more than 700 staff and one of Europe's leading centres in optics and micro-nanotechnology, where Lightspring co-founder Daniel Brunner serves as CNRS Research Director.

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

“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.” With this €350,000 grant and additional public innovation funding, Lightspring has now secured over €3.5 million in dilutive and non-dilutive financing to move its 3D optical coupling process from lab to production line.

According to Quentin Calleja, Principal at Atlantic, 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.”

Thomas Renaudin, Founding Partner at OVNI Capital, asserts that every generation of AI hardware pushes optics closer to compute, and co-packaged optics is where that ends up:

“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.”

The funding will support development of Lightspring’s PDK and design tools, expand the team to 12, fund co-design programmes with industrial partners, and scale and qualify its fabrication process for industrial use.