Active optical links embedded in flexible substrates

This paper presents the development of a fully embedded functional optical link in a flexible substrate, including embedded optical waveguides, light sources, detectors, and electronic circuitry. Embedding optical interconnections offers high-speed data connections to counter the fundamental bottlenecks of electrical interconnections such as speed, packaging, fan-out and power dissipation. Many research institutes (including ours ) have proven the integration concept on a rigid printed circuit board. The technology and the demonstrator in this paper take these optical interconnections one step further to flexible substrates. Standard commercially available GaAs VCSEL´s and GaAs photodetectors are thinned down to 30 mum, embedded into a flexible foil of optical transparent material and optically coupled with each other by means of embedded waveguides and out-of-plane micro-mirrors. The resulting structure shows good adhesion and very good flexible behavior and the embedded optical link has a total optical loss of 16 dB.