Cavity Soliton Laser Based on Mutually Coupled Semiconductor Microresonators

We report on experimental observation of localized structures in two mutually coupled broad-area semiconductor resonators, one of which acts as a saturable absorber. These structures coexist with a dark homogeneous background and they have the same properties as cavity solitons without requiring the presence of a driving beam into the system. They can be switched individually on and off by means of a local addressing beam.

Figure 1

Schematic drawing of the experiment. $L_1$: Laser above the transparency, $L_2$: Laser below the transparency, BS: beam splitter. Detection of $L_1$ ($L_2$) includes a CCD camera monitoring the near field of $L_1$ ($L_2$) and a fast detector to monitor the local temporal behavior.

Figure 2

Left: Local intensity output emitted by the system when scanning $I_{L_1}$ with all the other parameters constant. (A) below threshold, (B) lasing by feedback, (C) absorption by $L_2$, bistable behavior, (D) pattern formation. Right: Near field of both devices. Dark areas correspond to high intensities. (a),(b) Near-field image of $L_1$ ($L_2$), before the interaction ($I_{L_1}=180\mathrm{mA}$), (c),(d) Near field of $L_1$ ($L_2$), in the absorption zone ($I_{L_1}=358\mathrm{mA}$), (e),(f) Near field of $L_1$ ($L_2$), when the pattern is developed ($I_{L_1}=365\mathrm{mA}$). $L_2$ is slightly shifted on the left.

Figure 3

$L_1$ near-field intensity distribution. Dark areas correspond to high intensities. Sequence of successive switching of two independent structures with an incoherent writing beam (WB) tuned at the CS wavelength with all parameter fixed. (a) Both structures are off, (b) The injection of WB switches one structure, (c) the structure remains on after the WB is blocked, (d) the injection of the WB at a second location ignites a second structure, (e) when the WB is blocked, both structures are on, (f) reapplying the WB in the vicinity of the second structure attracts it to a slightly different location, (g) when the WB is blocked the structure switches off, (h) the WB is applied in the vicinity of the first structure to attract it to a slightly different location, (i) when the WB is blocked, both structures are off.