Design of Nearly Zero Dispersion Flattened Photonic Crystal Fiber with Double Cladding

A novel design of nearly zero dispersion flattened photonic crystal fiber (PCF) with double cladding is proposed. To employ traditional stack and draw technology, the cladding is composed of a traditional triangular lattice of air-holes and silica. The dispersion of the fiber is mainly engineered by the small air holes in the inner cladding, which are easily preserved in the fiber drawing procedure. The large air-holes in the outer cladding are mainly for light confinement. Thus, the dispersion property of the PCF is insensitive to the deformation of the air holes in the outer cladding. Using 8 layers of air-hole ring, the loss of the fundamental mode for the PCF is as low as 0.13dB/km at 1.55μm. The dispersion of the PCF fluctuates from -0.023 to 0.021ps・km^-1nm^-1 in the range 1.45-1.625μm.