Impact of input profile, absorption coefficients, and chirp on modulational instability of femtosecond pulses in silicon waveguides under fourth-order dispersion

Strong Modulation Instability in a Silicon–Organic Hybrid Slot Waveguide

“…The results obtained here represent a substantial improvement over those reported previously for the MI process. In the previous work [13], the MI gain was only less than 600 m À1 when the input peak power is 3 W. In another experiment [23], the signal got a gain of less than 50 dB in a 2-cm-long silicon photonic wire with a peak power of 13.5 W for the presence of the MI. Here, we would like to highlight that even if at the pump power P 0 ¼ 100 mW, the optical gain obtained in our work is above 1000 m À1 as seen from Fig.…”

“…We note that even in the normal dispersion region, the presence of the fourth-order dispersion 4 could render a nonzero imaginary part of K and thus induce the MI if the value of 2 is sufficiently small [12], [13]. Also, since the first term on the right-hand side of (5) is always real, the third-order dispersion plays no role in the MI process.…”

“…Significant works on the on-chip optical devices have already been reported, including parametric amplifier [1]- [3], Raman laser [4]- [7], broadband wavelength converter [8]- [10], and analog-to-digital converter [11]. In addition, modulation instability (MI) in which a weak perturbation of the amplitude or phase of a continuous wave (CW) or quasi-CW wave grows exponentially, has been studied in the silicon-based waveguide [12], [13]. The MI process could induce deep modulations of an input CW or quasi-CW which could play an important role in the design of on-chip ultra-short pulse train source.…”

“…Nevertheless, for pure silicon waveguides, the MI process at telecommunication band is usually destroyed by the strong two-photon absorption (TPA) and free-carrier absorption (FCA) [13]. In recent years, silicon-organic hybrid (SOH) waveguides have emerged as an attractive optical structure because of its ability to overcome the TPA-induced intrinsic limitations in pure silicon waveguides.…”

Ultrashort chirped pulse evolution in silicon photonic nanowires

“…The propagation of temporal solitons is affected by the inherent dispersion and nonlinear properties of silicon waveguides [1] along with linear losses that arise due to disorder scattering [3] . In addition, the initial chirp and shape distortion are inevitable and play a noticeable role in the pulse evolution [15] , which should be investigated further.…”