Observation of Discrete Surface Solitons

We report the first observation of discrete optical surface solitons at the interface between a nonlinear self-focusing waveguide lattice and a continuous medium. The effect of power on the localization process of these optical self-trapped states at the edge of an AlGaAs waveguide array is investigated in detail. Our experimental results are in good agreement with theoretical predictions.

Figure 1

(a) Normalized discrete surface soliton power $P$ versus the normalized eigenvalue $\mu$, where every line corresponds to a different soliton solution. The maximum of the field occurs at the $n=0$ waveguide site (solid line), $n=1$ waveguide site (dashed line), and $n=2$ waveguide site (dash-dot line). (b), (c) and (d) show the normalized intensity profiles when the maximum is at $n=0$, $n=1$, and $n=2$ waveguide sites, respectively. The inset in (a) depicts the array interface.

Figure 2

Intensity patterns observed at the output of the AlGaAs array for single channel excitation at three different peak input power levels injected into channel $n=0$. Left-hand side: experimental results for (a) $P=450\mathrm{W}$; (b) $P=1300\mathrm{W}$; (c) $P=2100\mathrm{W}$. Right-hand side: numerical calculation results for (d) $P=280\mathrm{W}$; (e) $P=1260\mathrm{W}$; (f) $P=2200\mathrm{W}$. The inset shows the actual sample geometry.

Figure 3

Intensity patterns observed at the output of the AlGaAs array for single channel excitation of the third ($n=2$) channel for three different input peak power levels.

Figure 4

Intensity patterns observed at the output of AlGaAs array for wide asymmetric beam excitation. (a) Beam is injected in the middle of the array; (b) Peak of the input beam profile is at the first ($n=0$) channel site. Output patterns for three different input peak power levels for each case are shown. The thick solid (green oline) line represents the intensity profile of the input beam. The vertical dashed line shows the position of the input beam peak.