Polymer optical fiber has advantages compared to other alternatives communication media such as copper, coax cable and glass fiber. POF has bigger bandwidth compared to wireless communication network and POF also free from electromagnetic disruption. POF is suitable for communication system up to distance of 100 meters with data speed of 400 Mbps using polymer step-index type. Thus, POF is effective for short haul data transmission. Applications of POF has widen nowadays including the Ethernet network at home or usually known as fiber to the home (FTTH) and in also used in automotive system. To increase the bandwidth of the transmission system, wavelength division multiplexing technique or WDM is applied in this study using optical splitter. Several signals with different wavelengths are multiplexed and carried over a single fiber and demultiplexed at the end of the communication system to obtain the original signal to be directed to the receiver. The advantage of the device developed in this study is that it is easy to construct and inexpensive. Thin-film is used as filter and two main color wavelength used are red and green thin-films. The red thin-film will absorb any other wavelength other than = 650 nm and the green thin-film will absorb any other wavelength that is not around = 510 nm. Characterization is done to test the signal strength with the existence of noise. Optical to noise ratio (OSNR) is measured to determine the optimum distance of the demultiplexer can work effectively. In this study, the maximum distance is taken up to five meters and the signal degradation is small. Although the signal strength decreases linearly with the length of the fiber as the noise increases, the demultiplexer works efficiently for short haul communication system.