fibre multimode à saut d'indice

CONT: Les fibres multimodes à saut d'indice possèdent un diamètre de cœur plus confortable (de 50 à 200 um). La frontière entre le cœur et la gaine présente une forte discontinuité d'indice. Dans ce cas, la propagation suit les lois de l'optique géométrique avec réflexion totale des rayons le long de cette frontière.

CONT: [The] step-index multimode fiber has a large core, up to 100 microns in diameter. As a result, some of the light rays that make up the digital pulse may travel a direct route whereas others zigzag as they bounce off the cladding. These alternative pathways cause the different groupings of light rays, referred to as modes, to arrive separately at a receiving point. The pulse, an aggregate of different modes, begins to spread out, losing its well-defined shape. The need to leave spacing between pulses to prevent overlapping limits bandwidth - that is, the amount of information that can be sent. Consequently, this type of fiber is best suited for transmission over short distances, in an endoscope, for instance.