This paper presents a novel and robust design for a new kind of photonic crystal fiber with dodecagonal and circular array of air holes, aiming at a highly nonlinear coefficient, ultra-flattened dispersion and ultra-low confinement loss. In this structure, circular lattices are added in two inner layers to obtain both ultra-low dispersion and ultra-flattened dispersion in a wide wavelength range. The proposed structure has a modest number of design parameters for easier fabrication. The finite difference method with perfectly matched boundary layer is used to analyze guiding properties. Analysis results prove that the proposed highly nonlinear dodecagonal photonic crystal fiber obtains a nonlinear coefficient greater than 43 (W.Km)-1 and low dispersion slope 0.003 ps/(nm.km) at 1.55 μm wavelength. Ultra-flattened dispersion of 0.8 ps/(km.nm) is also obtained ranging from wavelength 1.3 μm to 1.7 μm with confinement loss lower than 0.5×10-6 dB/m in the same wavelength range.
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