We numerically performed a way to produce a supratransmission phenomenon in the Salerno equation describing the dynamics of modulated waves in a discrete nonlinear transmission lattice. For the natural supratransmission phenomenon, there exists a threshold of amplitude for which energy can flow in the line. We show that gap transmission is possible with driven amplitude below the threshold due to the collision of different plane waves coming from both edges of the line. One of the two plane waves has a frequency in the forbidden gap, and another has a frequency in the allowed phonon band. During collision, the wave in the allowed band is considered as a perturbation of the ones in the forbidden gap.

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.

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.