Incoherent and coherent writing and erasure of cavity solitons in an optically pumped semiconductor amplifier

Interactions of the solitons in periodic driven-dissipative systems supporting quasibound states in the continuum

The paper is devoted to the dynamics of dissipative gap solitons in the periodically corrugated optical waveguides whose spectrum of linear excitations contains a mode that can be referred to as a quasi-bound state in the continuum. These systems can support a large variety of stable bright and dark dissipative solitons that can interact with each other and with the inhomogeneities of the pump. One of the focus points of this work is the influence of slow variations of the pump on the behavior of the solitons. It is shown that for the fixed sets of parameters the effect of pump inhomogeneities on the solitons is not the same for the solitons of different kinds. The second main goal of the paper is systematic study of the interaction between the solitons of the same or different kinds. It is demonstrated that various scenarios of intersoliton interactions can occur: The solitons can repulse each other or get attracted. In the latter case, the solitons can annihilate, fuse in a single soliton, or form a new bound state depending on the kinds of the interacting solitons and on the system parameters.

Extended stable equilibrium invaded by an unstable state

Coexistence of states is an indispensable feature in the observation of domain walls, interfaces, shock waves or fronts in macroscopic systems. The propagation of these nonlinear waves depends on the relative stability of the connected equilibria. In particular, one expects a stable equilibrium to invade an unstable one, such as occur in combustion, in the spread of permanent contagious diseases, or in the freezing of supercooled water. Here, we show that an unstable state generically can invade a locally stable one in the context of the pattern forming systems. The origin of this phenomenon is related to the lower energy unstable state invading the locally stable but higher energy state. Based on a one-dimensional model we reveal the necessary features to observe this phenomenon. This scenario is fulfilled in the case of a first order spatial instability. A photo-isomerization experiment of a dye-dopant nematic liquid crystal, allow us to observe the front propagation from an unstable state.

Writing and erasing of temporal cavity solitons by direct phase modulation of the cavity driving field

Temporal cavity solitons (CSs) are persisting pulses of light that can manifest themselves in continuously driven passive resonators, such as macroscopic fiber ring cavities and monolithic microresonators. Experiments so far have demonstrated two techniques for their excitation, yet both possess drawbacks in the form of system complexity or lack of control over soliton positioning. Here we experimentally demonstrate a new CS writing scheme that alleviates these deficiencies. Specifically, we show that temporal CSs can be excited at arbitrary positions through direct phase modulation of the cavity driving field, and that this technique also allows existing CSs to be selectively erased. Our results constitute the first experimental demonstration of temporal CS excitation via direct phase modulation, as well as their selective erasure (by any means). These advances reduce the complexity of CS excitation and could lead to controlled pulse generation in monolithic microresonators.

Response of laser-localized structures to external perturbations in coupled semiconductor microcavities

Laser-localized structures have been observed in several experiments based on broad-area semiconductor lasers. They appear as bounded regions of laser light emission which can exist independently of each other and are expected to be commuted via external optical perturbations. In this work, we perform a statistical analysis of time-resolved commutation experiments in a system of coupled lasers and show the role of wavelength, polarization and pulse energy in the switching process. Furthermore, we also analyse the response of the system outside of the stability region of laser-localized states in search of an excitable response. We observe not only a threshold separating two types of responses, but also a strong variability in the system's trajectory when returning to the initial stable fixed point.

Spatial localization in heterogeneous systems

We study spatial localization in the generalized Swift-Hohenberg equation with either quadratic-cubic or cubic-quintic nonlinearity subject to spatially heterogeneous forcing. Different types of forcing (sinusoidal or Gaussian) with different spatial scales are considered and the corresponding localized snaking structures are computed. The results indicate that spatial heterogeneity exerts a significant influence on the location of spatially localized structures in both parameter space and physical space, and on their stability properties. The results are expected to assist in the interpretation of experiments on localized structures where departures from spatial homogeneity are generally unavoidable.

Light-bullet routing and control with planar waveguide arrays

Spatial mode-locking in three dimensions can be achieved in a slab waveguide array architecture. This study focuses on using the resulting robust and self-starting light bullet formation for photonics applications. Specifically, light bullets can be manipulated through a simple electronically addressable spatial gain dynamics. By applying gain ramps in time and/or space via electronics technology, complete control and manipulation of the light bullets can be achieved, thus allowing for the construction of the master logic gates of NAND and NOR. Its robustness, self-starting behavior and easy addressability suggest that the slab waveguide array mode-locking merits serious consideration as a next generation photonics device.

Spatial mode-locking of light bullets in planar waveguide arrays

A theoretical proposal is presented for the generation of mode-locked light-bullets in planar waveguide arrays, extending the concept of time-domain mode-locking in waveguide arrays to spatial (transverse) mode-locking in slab waveguides. The model presented yields three-dimensional localized states that act as global attractors to the waveguide array system. Single pulse stationary and time-periodic solutions as well as the transition to multi-pulse solutions as a function of gain are observed to be stabilized in such a system.

Homoclinic snaking in a semiconductor-based optical system

We report on experimental observations of homoclinic snaking in a vertical-cavity semiconductor optical amplifier. Our observations in a quasi-one-dimensional and two-dimensional configurations agree qualitatively well with what is expected from recent theoretical and numerical studies. In particular, we show the bifurcation sequence leading to a snaking bifurcation diagram linking single localized states to "localized patterns" or clusters of localized states and demonstrate a parameter region where cluster states are inhibited.

Transverse spatial structure of a high Fresnel number Vertical External Cavity Surface Emitting Laser

The transverse spatial structure of an optically-pumped, Vertical External Cavity Surface Emitting Laser is investigated experimentally. The Fresnel number of the laser cavity is controlled with an intracavity lens. We show how the emission profile changes when passing from a low to a high Fresnel number configuration and analyze the RF spectrum of the total laser intensity. Though the laser operates in a multi-longitudinal mode configuration, the transverse profile of the laser emission shows well organized patterns.

Realization of a semiconductor-based cavity soliton laser

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. All-optical 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 mobility of these structures is also demonstrated.

Modeling pattern formation and cavity solitons in quantum dot optical microresonators in absorbing and amplifying regimes

We present a complete overview of our investigation past and present of the modelization and study of the spatiotemporal dynamics of a coherent field emitted by a semiconductor microcavity based on self-assembled quantum dots. The modelistic approach is discussed in relation to prospective growth and experimental research, and the model is then applied to resonators for which the medium is either passive (coherent photogeneration of carriers) or active (carrier pumping by current bias). The optical response of the system is investigated, especially in what concerns the linewidth enhancement factor, which turns out to be critical for the onset of self-organized patterns. The regimes in which one can expect bistable response, modulational instabilities, pattern formation, and cavity soliton formation are investigated. The pattern scenario is described, and experimentally achievable conditions are predicted for the occurrence of stable cavity solitons.

Localized traveling waves in vertical-cavity surface-emitting lasers with frequency-selective optical feedback

Spatially self-localized states have been found in a model of vertical-cavity surface-emitting lasers with frequency-selective optical feedback. The structures obtained differ from most known dissipative solitons in optics in that they are localized traveling waves. The results suggest a route to realization of a cavity soliton laser using standard semiconductor laser designs.