Abstract

Most designs for dispersion-flattened fibers reported in recent years are either bend sensitive¹ or are not truly single-mode at certain wavelengths of interest.² We propose a new class of dispersion-flattened fibers which support only one mode for λ > 1.28 μm, provide a total dispersion of <2 ps/km·nm over the 1.32-1.7-μm wave length range, and have a fundamental mode cutoff larger than 1.85 μm indicating that they suffer low bending losses. Furthermore, these fibers may be designed such that the chromatic dispersion vanishes at wavelengths in the neighborhood of 1.33 and 1.55 μm which correspond to the low attenuation windows of glass fibers. The proposed fibers have a step-index profile and consist of a central core, five inner claddings, and an outer cladding. The index differences are kept below 0.8% to ensure low losses due to Rayleigh and stress-induced scattering. An objective function is used to optimize the index profile with respect to (1) desired minimum dispersion, (2) wavelengths of zero dispersion, and (3) width of the dispersion-flattened window.

© 1989 Optical Society of America