Truncation-induced spectral broadening and subproducts generation in Airy-pulse-driven broadband cascaded four-wave mixing

We investigate truncation-induced spectral broadening and by-product generation in cascaded four-wave mixing (CFWM) driven by truncated Airy pulses (TAPs). Using a 3~m highly nonlinear fiber waveguide in a dual-pump configuration at telecommunication wavelengths (1530~nm and 1570~nm, each with 10~W peak power), we assess the impact of pulse asymmetry by comparing TAPs with symmetric profiles such as sech and first-kind Bessel pulses. Numerical simulations and analytical modeling show that the truncation coefficient <i>a</i> acts as a key tuning parameter controlling both the temporal energy localization and residual phase asymmetry, which jointly determine the CFWM efficiency. Increasing <i>a</i> enhances spectral broadening and the number of generated sidebands, even as the pulse becomes quasi-Gaussian, with its mean temporal center shifted toward positive times. Interactions between identical truncated Airy pulses yield the broadest and most asymmetric CFWM spectra under anomalous dispersion, while excessive truncation or nonlinearity leads to partial spectral incoherence, marking the onset of supercontinuum generation. A semi-empirical spectral coherence length <i>L</i>_coh and a critical truncation threshold <i>a</i>_Cr are introduced to quantify this transition. These results underscore the unique advantages of Airy-shaped pulses as versatile tools for tunable broadband light generation and nonlinear signal processing, and highlight the importance of the truncation parameter as a central control knob in CFWM dynamics.