Besançon startup Lightspring raises over €3.5 million to industrialise photonic chip packaging
French DeepTech startup Lightspring has raised over €3.5 million to move its 3D optical coupling technology from lab to production, targeting optical packaging costs that currently make up half of a photonic chip's price.
Lightspring, a DeepTech startup based in Besançon, France, that designs and manufactures optical interfaces for photonic integrated circuits, has closed a €3.1 million Seed round. 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 was also named a laureate of i-Lab, France's national DeepTech innovation competition, securing a €350,000 grant. Combined with the Seed round and additional public innovation funding, Lightspring has now raised over €3.5 million to move its 3D optical coupling process from the lab to a production line.
The problem being addressed
According to Lightspring, while photonic integrated circuit fabrication is now handled by a handful of mature foundries, assembly and optical packaging alone account for roughly 50% of a chip's cost, compared with around 20% for the foundry step itself. Fibre-to-chip coupling is still performed piece by piece through micrometre-scale active alignment, a process that brings 2-3 dB of typical optical loss, low throughput, degraded yield and no industry standard.
The technology
Lightspring uses 3D lithography, specifically two-photon polymerisation, to fabricate optical coupling structures — including microlenses, 3D waveguides and beam-shaping elements — directly onto the chip. This single process step handles fibre-to-chip, laser-to-chip and chiplet-to-chiplet coupling, targeting coupling losses below 0.5 dB per interface, without requiring precision pre-alignment. The approach is described as materials- and equipment-agnostic, and can complete design cycles in under two weeks, compared with several months for bespoke optical packaging.
The company was founded in 2026 in Besançon by Grégoire Bonnat, Adrià Grabulosa and Daniel Brunner. The underlying technology originates from research at the FEMTO-ST Institute, a joint CNRS-UMLP research unit with over 700 staff.
Plans ahead
Lightspring plans to use the new capital to develop its process design kit and design tools, and to hire staff in microfabrication, optical characterisation and photonic circuit design, growing the team to 12 people. It also intends to launch co-design programmes with industrial partners, focused on a co-packaged optics roadmap for AI infrastructure, and to scale and qualify its fabrication platform under industrial conditions.
