Study on Optical Features of Circular Photonic Crystal Fibers with Various Air-hole Size

: In this workwe proposed a newly designed photonic crystal fiber (PCF) with a circular lattice, the difference between the air-hole diameters of the first ring and the other rings makes it possible to improve the nonlinear properties of fibers.  We investigated the effect of varying the filling factor (d1/Ʌ) and lattice constant (Ʌ) on the nonlinear characteristics of photonic crystal fibers in the 0.5 - 2 µm wavelength range. The advantages of these photonic crystal fibers are the flat and near-zero dispersion, low attenuation, and high nonlinear coefficient. From simulation results, we have selected three optimal structures (Ʌ = 1.0 μm; d1/Ʌ = 0.4, Ʌ = 0.8 μm; d1/Ʌ = 0.6, and Ʌ = 0.8 μm; d1/Ʌ = 0.65) to analyze the nonlinear characteristics at the pump wavelengths. The proposed fibers are valuable for supercontinuum generation. 
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