ANALYSIS OF THE DECREASE IN ATTENUATION ACHIEVED BY PROPERLY BENDING PLASTIC OPTICAL FIBERS

When light propagates along a plastic optical fibre that bends sharply , an important amount of power can be lost through radiation around th e bend. An analysis is made of how to reduce the radiation loss by sha ping the bend into a suitable curve. To calculate the total radiation loss around the bend, a geometric approach to describing propagation i n multimode optical fibres is used. Radiation loss only occurs at refl ection or turning points, and is described by the power-transmission c oefficient T. For step-index optical fibres, T depends mainly on the a ngle of incidence at the interface and on the core and cladding refrac tive indices and, to a lesser degree, on the light wavelength. Differe nt bend shapes can cause very different radiation losses around the be nd. The purpose of this paper is to show which curves give rise to the lowest attenuations and identify the reasons.