Investigation of performance properties of plastic optical fibres used in a traffic light system

We investigate the performance properties of a multimode plastic optical fibre (POF) used in a traffic light system. An analytical function is proposed for predicting the angular power distribution at the output end of a multimode optical fibre when the beam at the input end of the fibre is centrally launched along the fibre axis. We demonstrate how mode coupling affects the output angular power distribution along the fibre and, therefore, the performance of optical fibre used as part of a traffic light system. It is found that as the length of the POF increases, the angular power distribution broadens until it reaches a length at which a steady-state distribution (SSD) is achieved. This broadening is insignificant at short POF lengths of up to 10 m. As a result, the effective radiation area at the output end of any long POF as part of different light systems, such as traffic, building, and bridge light systems, can be determined.