We compare numerically the supercontinuum generation (SCG) phenomenon in the Mid-Infrared (MIR) region through AsSe2/As2S5 chalcogenide based optical waveguides namely photonic crystal fiber (PCF) and rib-like structures. The same material combination is used in the two configurations for MIR-SCG. Specifically, the studied PCF is composed of a core made of AsSe2 glass and a surrounding cladding made of As2S5 glass while the AsSe2/As2S5 chalcogenide rib waveguide (AsSe2/As2S5-ChRW) is filled in its upper cladding by air while the lower one is constituted by the As2S5 glass. The comparison is conducted in the anomalous dispersion regime on a very short 1 mm-length of propagation for a 50 fs sech-type pulse in the HE11 mode at 4 μm wavelength for each waveguide. Despite the ultra-broadband and coherent MIR-SCG spectrum of 18.75 μm in bandwidth obtained with the considered AsSe2/As2S5-PCF, we found that an AsSe2/As2S5-ChRW that has a height H=1.98 μm and a width W= 5 μm allows a SCG spanning approximately from 1 beyond 20 μm with a very low energy as 0.4 nJ.

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We present the compression of Airy pulses in silicon-on-insulator (SOI) waveguides under the fourth-order dispersion (FOD) using the variational approach that involves Rayleigh’s dissipation function (RDF). All the pulse characteristics are under the influence of the two-photon and the frequency-carrier absorptions. In a quasi-linear approximation, the pulse compression conditions induced by the interaction of the group-velocity dispersion (GVD), the chirp and the FOD are derived. In the nonlinear case, the self-phase modulation (SPM), the two-photon absorption (TPA) and the free-carrier absorption (FCA) reduce the length of compression in a propagation regime of normal GVD, positive chirp and a negative value of FOD. The TPA reduces the maximal power reached than the SPM while the FCA rather increases its value. These results are confirmed in the general case where they all interact with the linear dispersion terms of the SOI waveguide.

In this paper, we report a numerical study of supercontinuum generation (SCG) using specially truncated Airy pulses in the mid-infrared (MIR) region of wavelengths through an AsSe ₂ /As ₂ S ₅ optical waveguide with rib-like structures modeled by the cubic-quintic nonlinear Schrödinger equation (CQNLSE). We use the waveguide studied by Diouf et al (2019 J. Lightwave Technol. 37 5692), which has been found interesting, as it can generate explosive spectra in the MIR domain. Through the anomalous dispersion regime, the spectral 20 dB bandwidths obtained have been found to exceed approximately 97250 nm. We also consider the effects on SCG spectra of quintic Kerr nonlinearity (QKN) and nonlinear photon absorptions (NPAs) such as two-photon absorption (TPA) and three-photon absorption (3PA). Without the NPAs, only the cooperative QKN is beneficial for the MIR-SCG. In the temporal domain, the emission of dispersive waves (DWs) is avoided by the presence of NPAs, while the cooperative nonlinearities perform this emission. Furthermore, if, in the cooperative case, we always neglect the 3PA and consider the TPA, we find an interesting spectral intensity (SI) of the SCG, compared with the case of competition between nonlinearities. Surprisingly, the 3PA appears to be a good tool for controlling the TPA because the SI is less reduced when the QKN cooperates with the cubic Kerr nonlinearity (CKN). In particular, if we consider the case of competition, the 3PA enhances the SI compared to the single TPA case (in which the 3PA is neglected) for larger wavelengths.

We investigate numerically the supercontinuum generation (SCG) phenomenon, using femtosecond pulses in the subnanoscale of energies through the generalized nonlinear Schrödinger equation that includes non-Kerr terms. Our results with 50 fs pulses in the anomalous dispersion regime show that, in comparison to the single cubic Kerr nonlinearity (CKN) case, the cooperative nonlinearities improve the spectral broadening, while the competing ones compress the spectral SCG bandwidth. Surprisingly, with the reduction of the pulse width, the cooperative nonlinearities induce a spectral compression while the competing ones keep the SCG bandwidth nearly constant from the input to the output of the considered waveguide. The increase of both the energy and the nonlinearity confirms this feature, showing that spectral compression is also obtained in the single CKN case, but less than in the case of cooperative nonlinearities.