Demultiplexer for WDM over POF in prism-spectrometer configuration

Polymer Optical Fibres (POFs) show clear advantages compared to copper and/or glass fibres. In essence, POFs are inexpensive, space-saving and not susceptible to electromagnetic interference. Thus, the usage of POFs have become a reasonable alternative in short distance data communication. Today, POFs are applied in a wide number of applications due to these specific advantages. These applications include automotive communication systems and In-House-Networking. The current transfer mode system via POF is based only on one channel (or rather on one wavelength), making the usable bandwidth the limiting factor of this technology. One potential solution to expand the usable bandwidth of POF-based systems is wavelength division multiplexing (WDM). Because of the attenuation behaviour of POF, the only transmission window is situated in the visible spectrum. The solution proposed in this paper makes it possible to transfer several signals on different wavelengths through a single polymeric fibre. In order to separate the transmitted signals, special separators - called demultiplexers - are utilized. These demultiplexers are realized by employing the principle of the prism-spectrometer. Thus, the signals transmitted over different wavelengths will not be refracted equally strong. In the set-up described in this paper, the light emitted by the polymeric fibre is collimated by an off-axis parabolic mirror and then broken up by a prism, making it possible to restore the data originally transmitted via each wavelength-channel.