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In this paper, benzene-core photonic crystal fibers (B-PCFs) with non-uniform air holes for the square lattice are studied by controlling the air-filling factor of the air holes in the first ring and increasing those up to a maximum for external holes. Commercial Mode Solutions software is used to study the influence of structural parameters on the nonlinear coefficient, dispersion, effective mode area, and attenuation. It can be seen that this design affects the linear and nonlinear properties at the same time. In other words, it has a crucial effect on either the near-zero flatness of dispersion or going up the nonlinearity and falling the loss of the B-PCFs. The above benefits make the optimized fibers suitable for supercontinuum (SC) generation applications. [ABSTRACT FROM AUTHOR]

A photonic crystal fiber made of fused silica glass and infiltrated with nitrobenzene (C6H5NO2) was proposed as a new nonlinear medium for supercontinuum generation (SG). The guiding properties of the fiber structure were studied numerically, including estimation of the effective refractive index, attenuation, and dispersion of the fundamental mode. Based on the obtained results, three optimized structures were selected and tested numerically for SG. With numerical simulations of nonlinear propagation, we demonstrated the feasibility of spectrally broad and coherent SG in the proposed structures. For the first we obtained a supercontinuum (SC) in the range of 0.8–1.8 µm, for the second in the range of 0.8–2.1 µm, and for the third 1.3–2.3 µm. The pulse energy was in the range of 0.06–0.5 nJ while the pulse duration was 90 fs or 120 fs. For all structures an SC was formed in the first centimeter of the light propagation and conveniently allowed to assume short segments of the fibers. The proposed fibers are good candidates for all-fiber SC sources constituting an attractive alternative to glass-core fibers, since the nonlinearity of nitrobenzene is significantly higher than that of silica. The proposed solution may lead to new low-cost all-fiber optical systems for SG. [ABSTRACT FROM AUTHOR]

In this paper, we compare dispersion characteristics of chloroform-core photonic crystal fibers (PCFs) with circular lattice and hexagonal lattice in the case of different air hole diameters. By varying lattice constant Ʌ and filling factor in the first ring d1/Ʌ, we can easily control chromatic dispersion and achieve three optimal structures for the circular lattice of fibers #CF1 (Ʌ = 1.0 µm, d1/Ʌ = 0.65), #CF2 (Ʌ = 1.0 µm, d1/Ʌ = 0.7), and #CF3 (Ʌ = 2.0 µm, d1/Ʌ = 0.3) and two optimal structures for the hexagonal lattice of fibers #HF1 (Ʌ = 1.0 µm, d1/Ʌ = 0.5), #HF2 (Ʌ = 2.0 µm, d1/Ʌ = 0.3). At the same structural parameter (Ʌ = 2.0 µm, d1/Ʌ = 0.3) and the corresponding pumping wavelength, the circular structure has a dispersion smaller by 5.598 ps/mn/km than the hexagonal lattice. #CF1 has all-normal dispersion with the peak of the dispersion curve asymptote to the zero-dispersion curve which is very suitable for coherent supercontinuum generation (SCG). The #HF1 structure has a near-zero flat anomalous dispersion in the wide wavelength range from 1.1 µm to 1.4 µm. Our results will be an important premise in choosing a PCF structure to study SCG. [ABSTRACT FROM AUTHOR]