Bài báo khoa học

In this paper, we simulate and compared the effective mode area and the nonlinear coefficient of circular and rectangular lattices photonic crystal fibers (PCFs) structures when infiltrating carbon disulfide (CS2). By changing the lattice constant Ʌ = 1.0 µm; 1.5 µm; 1.8 µm, and 2.0 µm with the filling factor d1 /Ʌ from 0.3 to 0.8 to change the core diameter Dc (Dc = 2Ʌ - 1.2d1, there d1 is the first ring diameter), we have selected 02 structures of the circular lattice of fibers #CF1 (Ʌ = 1.0 µm, d1 /Ʌ = 0.75, Dc = 1.1 µm), #CF2 (Ʌ = 1.0 µm, d1 /Ʌ = 0.8, Dc = 1.04 µm) and 02 structures of the rectangular lattice of fibers # F1 (Ʌ = 1.0 µm, d1 /Ʌ = 0.75, Dc = 1.1 µm), and #RF2 ( Ʌ = 1.0 µm, d1 /Ʌ = 0.8, Dc = 1.04 µm). When comparing the effective mode area and nonlinear coefficient of these optimal structures, we found that at the same structural parameters with the same pump wavelength of 1.55 µm, the #CF1 has an effective mode area smaller by 0.137 µm2 and the nonlinear coefficient is higher by 5170 W -1.km -1 than the # RF1; these results correspond to 0.138 µm2 and 2820 W -1 .km -1 when comparing two fibers #CF2 and #RF2. From this, we show that when CS2 is infiltrated into the core, we have found the optimal PCF fibers with a small effective mode area and high nonlinear coefficient there the circular lattices are more optimal than the rectangular lattices. The structures we propose are very suitable for the study of supercontinuum generation (SC) in the near-infrared region.