Light propagation in a fibre-brush-shape converter

Optical fibres play more and more important roles in astronomy, for example, to transfer light from the focus point of telescopes to spectrometers. In this paper, a novel designed, a fibre-brush-shape converter was designed to transfer circle input of a fibre to a line-shape output. The brush-shape converter consists of several bare fibres at one end, one fibre at the other end and a taper between them. The light propagating from the bare fibres to the single fibre will be coupled. According to the theoretical and calculated results, the power of the light could be confined in the core of the fibre if the parameters of the taper are appropriate.