OPTICAL FIBER-BASED DISPERSION COMPENSATION USING HIGHER-ORDER MODES NEAR CUTOFF

Higher order spatial modes in optical fibers exhibit large, negative chromatic dispersion when operated near their cutoff wavelength. By using a spatial mode-converter to selectively excite a higher order mode in specially designed multimode fiber, this dispersion can be used to compensate the positive dispersion in conventional single-mode fiber spans. In this paper, issues related to compensating fiber and mode-converter design are explored. Experimental measurements in specially designed two-mode fibers operated in LP11 mode show negative dispersion as large as -770 ps/nm.km at 1555 nm. Pulse propagation and system experiments employing spatial mode-converters to excite LP11 mode in a two-mode fiber demonstrate the feasibility of this technique for dispersion compensation in lightwave systems.