The Polymer Optical Fiber (POF) has certain advantages over alternative data communication media such as glass fibers, copper cables, and wireless systems. It is pliable, durable, and cost effective, has small weight and a short bend radius, allows easy installation and quick troubleshooting, and provides immunity to electromagnetic interference. Due to its advantages, POF is a promising candidate for broadband in-house networks. Among different types of POF, the 1 mm PMMA Step-Index POF (SI-POF) is the best known and by far the most widely used type of POF. Present communication systems over POF use a single channel for data transmission. To increase the capacity of a single POF, multiple bandwidth-efficient channels can be transmitted over the same fiber. The technique is known as wavelength division multiplexing (WDM).

This paper reports on the current development status of a four-channel coarse WDM (CWDM) transmission system for Multi-Gbit/s in-house data communication via SI-POF. The block diagram of the experimental setup and the complete description of established communication system will be given in the full paper. The key photonic component in a CWDM system under development is a demultiplexer (DEMUX). To spatially separate different wavelength channels, a four-channel DEMUX with low insertion loss (<6 dB) and low crosstalk (<-30 dB) is realized in bulk optics technology at the Harz University. The operating principle, the description of the opto-mechanical setup, and the transfer function of the DEMUX will be shown. In addition, an optical link power budget analysis, based on the experimentally obtained data, will be carried out for all four channels. Finally, Multi-Gbit/s data transmission experiments will be performed with violet, blue, green, and red laser diodes via up to 25 m SI-POF links, and the results and their analysis will be presented.