IN Brief:
- Demcon Photonics is developing an alternative to conventional active alignment of fibre arrays and photonic integrated circuits.
- Computer vision identifies optical interface positions before a femtosecond laser writes connecting waveguides into glass.
- Prototype development is under way, with an early-2027 demonstrator planned and industrial manufacturing performance still to be established.
Demcon Photonics is developing an optical assembly process that uses direct laser writing to connect fibre arrays with photonic integrated circuits. The Dutch engineering company proposes measuring the positions of individual optical interfaces and forming matching waveguides inside glass, providing an alternative to the mechanical alignment procedures used when attaching multiple fibres to a photonic chip.
Fibre-to-chip alignment is a demanding stage of photonic assembly because the optical structures being connected must transfer light with sufficiently low losses. The interfaces are small, and even modest positional differences can affect how effectively light passes between a fibre and the corresponding waveguide on a chip. As the number of optical channels increases, maintaining suitable alignment across the complete array becomes more difficult.
Conventional active alignment addresses this problem by transmitting light through the connection while adjusting the relative positions of the components. The assembly equipment monitors the optical response and moves the fibre array or chip until an acceptable coupling position is found. Once aligned, the components must be secured without introducing displacement that compromises the optical connection.
The method becomes more complicated when the geometry of an array differs from its nominal design. Slight warpage, dimensional variation, or differences in individual interface positions can mean that moving an entire fibre array improves alignment at one channel while leaving another less accurately positioned. A single mechanical adjustment cannot always compensate for variations distributed across several optical connections.
Demcon’s proposed process changes how those positional differences are accommodated. Computer-vision measurements establish the actual positions of the individual fibres and the relevant interfaces on the photonic integrated circuit. The measured geometry is then used to determine the routes required for optical waveguides within a glass interconnect structure.
A femtosecond pulsed laser writes those waveguides directly into the glass. The short optical pulses are focused within the transparent material, where their interaction can produce local changes in refractive index under suitable processing conditions. By moving the focused region along a defined path, the equipment creates a structure capable of guiding light through the material.
The route can be adapted to the measured positions of the connected interfaces rather than relying on one fixed waveguide geometry for every assembly. This creates a potential way to accommodate differences between fibre arrays and chips through the optical interconnect itself. Accurate measurement remains essential because the written paths must still meet the relevant optical structures at their actual locations.
Waveguide design also influences optical performance. Light travelling between a fibre, a laser-written glass structure, and a photonic chip encounters interfaces whose optical modes may have different dimensions and characteristics. Mode mismatch, positional error, propagation loss, and the geometry of bends or transitions can contribute to insertion loss across the completed connection.
Writing a route that follows the measured component positions does not independently establish that the resulting optical loss is acceptable. The process must produce waveguides with suitable optical characteristics and repeatable connections at both ends. Demcon identifies minimal coupling loss as a development objective, but has not disclosed quantified insertion-loss measurements for a completed industrial assembly system.
The manufacturing process must also account for the time needed to measure the interfaces, calculate the required routes, write the waveguides, and inspect the finished connections. These operations contribute to the overall assembly cycle. A reduction in mechanical adjustment time would be useful only if the combined measurement and laser-processing sequence can achieve the required production rate.
Process yield is equally important. Photonic assemblies containing several optical channels must satisfy the required performance conditions across those channels, and defects in one connection may affect the acceptability of the complete assembly. Repeatable waveguide writing, controlled component positioning, and suitable inspection procedures will therefore determine how effectively the proposed technique can be transferred to industrial production.
Demcon intends to act as a systems integrator, combining existing direct laser-writing technology with its experience in opto-mechatronics, metrology, automation, and manufacturing equipment. The laser-writing principle is already used in other areas, including glass micromachining and microfluidics. The planned development concentrates on integrating the relevant technologies into equipment suitable for photonics assembly rather than inventing the underlying laser process.
The company is seeking collaboration with both laser-processing technology developers and manufacturers of photonic products. Equipment developers could contribute processing hardware and expertise, while photonics manufacturers would provide application requirements and components against which the production method could be assessed. Integrating those contributions will require the measurement, writing, handling, and inspection operations to function as one manufacturing sequence.
Such integration is particularly relevant to assemblies containing multiple optical channels, where the production equipment must control the relationship between mechanical tolerances and optical performance. Different photonic products can impose different requirements for fibre spacing, waveguide geometry, coupling structures, and packaging. The suitability of the method will therefore depend on the types of assemblies selected for development and the results achieved under representative production conditions.
Demcon is working on prototypes and plans to present a demonstrator to prospective partners in early 2027. The company has not yet published a qualified production throughput, measured yield, or a distribution of coupling-loss results for the proposed equipment. Those parameters will determine whether the technology can provide a practical alternative to active alignment at industrial scale.
The current programme establishes an engineering route based on measuring optical interfaces and writing the corresponding connections, with Demcon coordinating the development of a complete manufacturing process. The planned demonstrator will provide the next opportunity to assess its optical performance and the time required to assemble multiple connections.
