Lightspring raises €3.1M to fix photonic chip packaging bottleneck
What's the deal? French deeptech startup LightspringDealroom has a profile for this one. Try Dealroom → has raised a €3.1 million seed round co-led by AtlanticDealroom has a profile for this one. Try Dealroom → and OVNI CapitalDealroom has a profile for this one. Try Dealroom →. Concept VenturesDealroom has a profile for this one. Try Dealroom →, IxcoreDealroom has a profile for this one. Try Dealroom →, Plug and Play VenturesDealroom has a profile for this one. Try Dealroom →, and industry angels also joined.
What's the endgame? Lightspring designs and manufactures the optical interfaces of photonic integrated circuits (PICs). It applies 3D lithography directly onto the chip, turning packaging — the most expensive and least reproducible step in the chain — into a programmable manufacturing step.
Why now? Every generation of AI infrastructure pushes optics closer to compute, moving the optical interface onto the substrate. But assembly and packaging account for roughly 50% of a PIC's cost, against around 20% for the foundry step.
Today, fibre-to-chip coupling is done part by part through micrometre-scale active alignment, bringing 2–3 dB of typical optical loss, low throughput, and no standard. Lightspring targets coupling losses below 0.5 dB per interface in a single step, cutting design cycles to under two weeks from several months.
What's under the hood? The technology uses two-photon polymerisation to fabricate microlenses, 3D waveguides, and beam-shaping elements directly on the chip. It originates from research at the FEMTO-ST Institute in Besançon, where co-founder Daniel Brunner serves as CNRS research director.
Lightspring was also named a laureate of i-Lab, France's national deeptech competition. With a €350,000 grant and other public funding, it has secured over €3.5 million in dilutive and non-dilutive financing to move its process from lab to production line.
What they're saying: "Light still loses most of its energy the moment it enters or leaves the device," said co-founder and chief executive officer Grégoire Bonnat. "This funding will turn a lab result into a qualified industrial building block."
Atlantic principal Quentin Calleja said photonics is scaling into AI infrastructure fast, but optical packaging remains slow and expensive. "Lightspring has developed a technology that finally makes it scalable," he said.
The signal: The round ranks among the top 10% of all-time seed deals in France by size, a marker of investor appetite for deeptech tied to AI infrastructure. As OVNI Capital's Thomas Renaudin put it, the industry has the roadmap but not a way "to manufacture the optical interface at volume" — the gap Lightspring aims to fill.
Read more: Tech.eu
Image credit: Generated with Gemini
