1. Field of the Invention
The present invention relates to a circuit board assembly including at least one circuit board with at least one embedded optical waveguide which has at least one locally bent part reaching at least an upper/lower external surface of the circuit board to enable its coupling to an optical input/output device.
2. Background Information
Such a circuit board assembly is generally known in the art, e.g. from the U.S. Pat. No. 3,872,236.
In this known assembly the waveguide is an optical fiber which is embedded in a substrate, the bent part of which reaches the surface of the broad, this bent part being polished or cut to form a tap enabling its coupling with the input/output device.
Light transported by the fiber either leaves the latter at the location of the tap under a well defined angle which depends on the curvature of the fibre, or is injected therein under a well-defined angle. As a consequence, the input/output device has to be coupled to the fiber either by abutment contact with the tap, or by using optical devices such as lenses, prisms, holograms etc, to guide the light from/to the input/output device to/from the fiber tap at the required angle.