The realization of a cavity soliton laser using a vertical-cavity surface-emitting semiconductor gain structure coupled to an external cavity with a frequency-selective element is reported. Alloptical control of bistable solitonic emission states representing small microlasers is demonstrated by injection of an external beam. The control scheme is phase-insensitive and hence expected to be robust for all-optical processing applications. The motility of these structures is also demonstrated.

We study the decrease of the ground-state output with increasing current in two-state quantum dot lasing. We show that the asymmetry in the thermal population redistribution breaks the symmetric dynamical evolution of the electron-hole pairs. This fully explains the transition from two-state to single-state lasing observed experimentally. The model also reproduces the temperature dependence of the two-state lasing. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1995947͔Laser devices based on self-assembled quantum dots are a promising source of new physics. 1 The three-dimensional ͑3D͒ confinement of the carriers induces a discrete density of states that implies, for instance, a reduction of the threshold current, 2 a low chirp, a weak temperature dependence, 3 and a reduced sensitivity to optical feedback 4 at telecom wavelengths on GaAs substrates. The recombination of groundstate ͑GS͒ electrons and holes leads to GS lasing but recombination of excited-states ͑ES͒ electrons and holes can also lead to lasing at lower wavelengths. The occurrence of a secondary threshold, involving a second electron-hole pair of levels, was predicted for a sufficiently high bias. 5 Increasing the current further, the ES will eventually become the only surviving line at the expense of the GS transition. 6-9 For injection rates exceeding the second threshold, theory only predicts up to now that the GS intensity becomes a constant while experiments display a reduction down to zero of the GS emission. The aim of this Letter is to analyze both experimentally and theoretically this behavior.The self-organized quantum dot ͑QD͒ active region heterostructure consisted of six InGaAs QD layers embedded in quantum well using dots in a well ͑DWELL͒ technology. 10 Single transverse mode ridge waveguide lasers were fabricated with lengths of 750 m, 1 mm, 1.5 mm, and 2 mm, ridge widths ranging from 3 to 5 m, and a depth of 0.9 m. Both facets were left uncoated. These devices were mounted epitaxial side up on Peltier-controlled copper heat sinks. While long devices emitted in the GS near 1310 nm, 1-mm-long devices emitted first in the GS but then also in the ES ͑1240 nm͒. The shortest devices emitted in the first excited state for all currents. The light-current curves, characteristic of a 1-mm-device obtained in both cw and pulsed regimes, are shown in Fig. 1. In both cases, as the injection current increases, there is a current range where the power in GS decreased while the power state in ES increased as previously observed. [6][7][8][9] It is also worth to note that the differential efficiency is larger for the ES, as shown on Fig. 1, highlighting its increased density of states. Operation in the pulsed regime is necessary to remove the role of thermal effects. Figure 1 corresponds to a pulse width of 100 ns duration with a repetition rate of 100 kHz. We verified that the behavior is similar with pulse widths down to 6 ns. The qualitative invariance of the dynamical response with respect to the pulse duration indicates that Joule heati...

The properties of cavity solitons in a vertical-cavity surface-emitting laser with frequency-selective feedback from a diffraction grating are characterized and analyzed. The solitons have a typical width of 10 m and a linewidth of down to 10 MHz, i.e., they represent small microlasers. Their equilibrium spatial location arises from an interplay of spatial inhomogeneities in the device and a grating-induced force which depends on detuning. Transients involve the passage through a self-pulsing state. Due to the grating-induced advection, drifting excitations are found, which might have applications in all-optical delay lines though their solitonic nature remains to be established. (Taken from : http://pra.aps.org/pdf/PRA/v78/i2/e023810

We analyze experimentally the intensity oscillations of the longitudinal modes of quantum dot semiconductor lasers. We show that the modal intensities can oscillate chaotically with different average frequencies, but obey a highly organized antiphase dynamics leading to a constant total output power. The fluctuations are in the MHz range. We report the first experimental observation of frequency clustering associated with synchronization. We also observe the propagation of perturbations across the optical spectrum from blue to red. DOI: 10.1103/PhysRevLett.96.053902 PACS numbers: 42.65.Sf, 05.40.Ca, 05.45.ÿa, 42.65.Pc Coupled oscillators exhibit many interesting features that appear naturally in everyday life [1,2]. Such systems can be broadly divided into either globally coupled, where each oscillator is directly influenced by each of the other oscillators, or locally coupled, where nearest-neighbor interactions dominate. Synchronization occurs in both types of systems. The appearance of one or more clusters, where each cluster consists of a subset of synchronized oscillators, was predicted for globally coupled systems in the framework of the Kuramoto model [3]. In lasers, synchronization has been harnessed to achieve phase locked arrays of lasers which deliver high brightness outputs (local coupling) [4] and mode-locked lasers resulting in very short optical pulses (global coupling). Fundamental studies of chaotic state locking have also been examined in multimode lasers; e.g., two coupled modes of a ring laser can exhibit chaotic phase synchronization [5]. Globally coupled multimode lasers also exhibit antiphase dynamics [6,7]. Antiphase dynamics was studied theoretically and experimentally in diverse globally coupled systems such as Josephson junctions [8], chemical oscillators [9], and olfactory systems [10].The aim of this Letter is to report the first experimental evidence, to our best knowledge, of clustering effects associated with synchronization. This was achieved by analyzing the intensity oscillations of the longitudinal modes of quantum dot semiconductor lasers. Each laser has up to 40 longitudinal modes where each lasing mode displays large amplitude chaotic fluctuations although the total laser output power remains almost constant. The fluctuations measured in each mode occur at frequencies of tens of MHz, which is much smaller than the frequency difference between two consecutive modes (25 GHz) and the laser's relaxation oscillation frequency (>1 GHz). Modal fluctuations in quantum well lasers at similar frequencies, known as mode partition, have previously been interpreted as a noise induced phenomenon [11]. However, our measurements indicate several deterministic features which cannot be accounted for by such a description. We observe that groups of modes may have the same frequency indicating the appearance of clustering. We also observe the propagation of perturbations across the optical spectrum from blue to red similar to those observed in quantum well semiconductor lasers [12]. Transi...