Dispersion-shifted dual-shape core fibers. Optimization based on spot size definitions

Design features, for very low bend and splice losses, in dispersion-shifted dual-shape core (DSC) single-mode fibers are obtained in terms of characteristic mode spot sizes W responsible for splice loss, and W/sub infinity / responsible for bend loss. Dual-shape core fiber designs are given with W/sub infinity //W lying between 1.16 and 1.33 while maintaining the mode spot size between 4 and 5 mu m at the operating wavelength of 1550 nm. With this design goal it is shown that bending loss would be lower in a step-index than in a graded-index DSC fiber. Further, conventional single clad step-index or triangular-index dispersion-shifted fibers are seen to have higher bending loss than well-designed DSC fibers.< >