A doubly clad fiber with a right-handed-material core and outer cladding but a left-handed-material inner cladding has been analyzed in weakly guiding approximation. The characteristic equations for four kinds of guided modes (HE, EH, TE, and TM) are derived and further simplified under far from cutoff condition. Dispersion curves for the lowest-order mode of each of the four modes have been calculated for different inner-cladding refractive index and thickness. Compared with corresponding curves for a common right-handed doubly clad fiber, these curves all behave with abnormal dispersion. Near cutoff, double degeneracy occurs for and modes.
© 2007 Optical Society of America
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