Exact fit; 0,1 micrometer

Why this is important

The sharp increase in data traffic (internet) is approaching the limits of the current broadband technology. Although glass fibres are able to transport large volumes of optical data, the intersections where the optical data must be transformed into electronic information pose a problem.

The bundle of light passing through a glass fibre is as thin as one tenth of a human hair. The connections between optical chips and laser diodes must therefore be very precise. Micro-engineer Dr Marcel Tichem (3mE) has achieved a precision of 0.1 micrometre (700x thinner than a human hair). In 2008, one of his doctoral candidates produced a ‘box’ (opto-electronic package), in which the core of a glass fibre is aligned precisely with a laser diode. This is done with a micro-electromechanical system (MEMS) that can move the thin end of the glass fibre in two directions (horizontal and vertical).

Tichem is now working on the next challenge: connecting the light signals of a photonic chip. This involves four minuscule streams of light (‘wave guides’), each with a diameter of 3 micrometres, which are emitted from a photonic chip at a distance of 25 micrometres from each other. Connecting glass fibres to them, however, requires an intermediate chip (an ‘interposer’), which broadens the light streams and their distance from each other. Even when this interposer chip, with its studs and grooves (a bit like Lego) is in place, it is impossible to achieve a precision smaller than 0.5 micrometre, although 0.1 is required.

Tichem resolves this problem by incorporating MEMS functions in the interposer. After the photonic chips have been installed, he can use the microelectromechanical system to manoeuvre the streams of light precisely into place. The system also allows him to achieve optical connections for several light streams at once.

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