Analysis and design of multi-clad single mode fibers with three zero-dispersion wavelengths

The authors propose a series of single-mode dispersion flattened fibers with three zero-dispersion wavelengths, which have potential for long-distance communications and for wavelength-division-multiplexing application throughout the entire spectrum range from 1.3 μm to 1.6 μm. The fibers were studied in the weakly guiding limit for the low-order modes. The zero-chromatic dispersion wavelength of these fibers is less dependent on cladding index variations than those of the double-clad and quadruple-clad fibers. Results demonstrating a total dispersion of ±0.95 ps/km-nm over the entire spectral range between 1.3 μm and 1.6 μm are presented. Such dispersion-flattening is achieved while simultaneously maintaining a spot size with a radius of 4.33 μm to 5.13 μm at a 1.55-μm wavelength. The matrix method is used to compute the mode propagation constants and field distributions. An objective function is applied to optimize the fiber-index profile to achieve total zero dispersion at desired wavelengths