Observation of Resonance Soliton Trapping due to a Photoinduced Gap in Wave Number

We investigate the nonlinear propagation of two forward propagating modes coupled by a resonant traveling-wave grating, which is photoinduced by illuminating an optical fiber with a beat signal. This interaction, representative of systems whose dispersion relation $K=K(\Omega )$ exhibits a gap in momentum $K$, shows evidence of localization mediated by resonance solitons. The signature of a still (in the grating frame) soliton is grating-induced cancellation of modal group-velocity mismatch.

Figure 1

(a) Dispersion relation $\Delta \omega$ vs $\mathrm{Re}[k]$ for FWC. Insets: Modal power evolutions $P_{1,2}(Z)=|E_{1,2}{|}^2$ for marked values of $|\Delta \omega |$ when mode 1 is launched [$P_{1,2}$ and $Z$ are in units of $P_1(0)$ and grating length $L$, $|\Gamma |L=6$]. (b) As in (a) for BWC with insets relative to launching the forward mode 1 [$P_{1,2}$ in units of $P_1(L)$, $|\Gamma |L=3$].

Figure 2

Signal power evolution $|E_s(Z,T){|}^2$ of a soliton input in the absence (a) or presence (b) of the grating wave $E_g$, as obtained from the NLSEs (1) with parameter values of our experiment (see text). The inset in (b) shows the output signal power compared with the input envelope (dashed line).

Figure 3

Scheme of the experimental setup.

Figure 4

Output spectral density $S(\lambda )$ (linear scale) measured with (solid line, $P_g=16\mathrm{W}$) and without (dashed line) the input grating, when only the blueshifted (${\lambda }_{s1}$) signal pulse is launched. The inset shows the corresponding log scale plot.

Figure 5

Streak camera traces of the output signal obtained when two equally intense signal pulses are colaunched with grating waves of peak power $P_g$ [increasing from (a) to (d)]. The dashed curve in (d) shows the profile corresponding to the trapped signal, as obtained numerically from NLSEs (1).