MATCHING OF A BENT STEP-INDEX SINGLE-MODE FIBER BY A MODAL EQUIVALENTSLAB WAVE-GUIDE STRUCTURE

A novel procedure of matching the modal properties of a bent step-inde x single-mode fiber (BSSF) by the ones of an equivalent slab waveguide (ESW) structure is presented. On applying this procedure the actual B SSF structure is modelled in the first step by an equivalent straight anisotropic single-mode fiber (SASF) and in the second step this SASF structure is modally matched by an ESW structure. It is shown that for given BSSF (or SASF) input parameters only the derived ESW parameters can describe the modal features (birefringence, cut-off thickness and wavelength, single-mode operation range as well as the numerical aper ture) of an actual BSSF structure rigorously and consistently within t he framework of a slab model analysis.