摘要： Threshold effects and trapping subsequent to the collision of a projectile wave packet and a target are ubiquitous in quantum mechanics. In nonlinear optics, the interaction between a soliton (S) and a dispersive wave (DW) exhibits similarities to wave-packet scattering and offers means for all-optical control [1]. However, threshold effects akin to those in quantum mechanical potential scattering when a bound-state eigenvalue is close to the continuum, and generation of metastable states due to scattering resonances, are not directly allowed. Such phenomena are of high interest in the context of optical technologies concerning storage and manipulation of optical data. Here, we exploit an elaborate yet fabricable nonlinear waveguide [2] to realize an all-optical analogue of a quantum mechanical potential well in terms of the refractive index change induced by a solitary wave. Besides threshold effects this allows for an unexpected trapping mechanism with the ability to engineer metastable states with controllable lifetimes. Observation of the above effects requires S and DW to copropagate at nearly identical group velocities. Our setup features an alternating sequence of regions of normal dispersion (N1?N3) and anomalous dispersion (A1, A2), exhibiting group delay and group velocity dispersion pro?les shown in Figs. 1(a,b). We use numerical simulations of an unidirectional propagation equation for the analytic signal [3]. Firstly, we demonstrate threshold effects in the collision of a “projectile” DW in A2 and a “target” soliton in A1, manifested by peaks in the fraction of transmitted DW energy (Fig. 1(c)) and culminating in its re?ectionless transmission at integer potential strengths νeff de?ned by the DW center frequency (Fig. 1(d)). Off-threshold, interference with re?ected DW components causes a polychotomous wave train (Fig. 1(e)). As evident from the spectrograms in Figs. 1(h,i), inside S, DW exhibits a time-domain structure resembling the quasi bound state closest in νeff. Secondly, we show that a projectile DW launched in N3, colliding with a target soliton in A1, experiences a partial down-shift to a frequency range in A2, group-velocity matched to the soliton. The down-shifted frequency components perceive the soliton as time-domain potential-well to which they are con?ned. Nonzero overlap of the trapped state with the adjacent region of normal dispersion causes its decay, resulting in metastability. Trapping and decay of a metastable state (Figs. 1(f,j)) might also lead to a huge time-delay (Figs. 1(g,k)). We further observe re?ectionless transmission, total (bounce-off) re?ection and trapping in the collision of unequal solitons residing in different regions of anomalous dispersion. Besides the fundamental aspect of providing a quantum analog system, this might pave the way for new applications in optical technologies such as all-optical manipulation of data.