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.