Numerical Investigation of Bright Soliton-Like Pulse Evolution in Silica- and CS_2-Core Suspended Photonic Crystal Fibres

Source abstract

Photonic crystal fibres (PCFs) permit substantial control of dispersion and nonlinearity through geometry and core-material selection, making suspended and liquid-core designs attractive for nonlinear pulse manipulation. This study examines bright soliton-like pulse evolution in silica-core and carbon disulfide (CS2)-core PCFs using a generalized cubic–quintic nonlinear Schrödinger equation that retains second-, third-, and fourth-order dispersion. Fibre coefficients at 1.55 μm were taken from a previously published finite-element characterisation of suspended PCFs. Pulse propagation was solved directly with a symmetric split-step Fourier method rather than assuming a closed-form travelling-wave solution. A hyperbolic-secant input with T0 =0.5 ps was used, with the input peak power scaled to the conventional fundamental-soliton condition of the unsuspended member of each material family. Over four baseline dispersion lengths, the unsuspended silica and CS2 cases remained nearly invariant, whereas core suspension produced measurable temporal compression. For silica-core PCFs, the minimum intensity full width at half maximum (FWHM) decreased from 0.881 ps at the input to 0.748 ps for suspension factor (SF) 1.222 and 0.394 ps for SF 1.444, corresponding to compression factors of 1.18 and 2.24. For CS2-core PCFs, the corresponding minimum FWHM values were 0.777 and 0.557 ps, with compression factors of 1.13 and 1.58. Grid-refinement tests changed the strongest-compression FWHM values by less than 0.01%, and relative pulse-energy drift remained below 5*10-10. Because the dispersion and nonlinear coefficients vary simultaneously with suspension, these results should be interpreted as responses of the complete parameter sets rather than as isolated effects of individual coefficients. The calculations support suspended PCFs as tunable platforms for short-pulse reshaping while defining the numerical and physical conditions under which the comparison is reproducible.