Light-propagation characteristics in thermally diffused expanded core fibers

Characteristics of light propagation in thermally diffused expanded-core (TEC) fibers are analyzed. Changes in the modal-field distributions along fibers and transition losses are obtained by use of the propagating-beam method. It is found that a transition length sufficiently longer than the characteristic length is necessary to expand or reduce the field diameter with low losses. A simplified model for understanding the mechanism of light propagation in TEC fibers is presented. Transmission losses between TEC fibers having imperfect splices are measured, the results are compared with those obtained by a simple theory and an exact theory.<
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