Mathias Marconi

How Laser Localized Structures evolve out of Passive Mode-Locking

We investigate the relationship between passive mode-locking and the formation of temporal localized structures in the output of a laser, allowing for individual pulse addressing and arbitrary low repetition rates.

Passive Mode-Locking and Tilted Waves in Broad-Area Vertical-Cavity Surface-Emitting Lasers

We show experimentally and theoretically that an electrically biased 200-μm multitransverse mode vertical-cavity surface-emitting laser can be passively mode-locked using optical feedback from a distant resonant saturable absorber mirror. This is achieved when one cavity is placed at the Fourier plane of the other. Such nonconventional optical feedback leads to the formation of two tilted plane waves traveling in the external cavity with opposite transverse components and alternating in time at every round-trip. Each of these plane waves gives birth to a train of mode-locked pulses separated by twice the external cavity round-trip, while the two trains are time shifted by a round-trip. A large portion of the transverse section of the device contributes to mode-locked emission leading to pulses of approximately 1-W peak power and 10-ps width. We discuss how inhomogeneities in the transverse section of the saturable absorber select the emitted tilted waves, thus leading to tunable emission over 4 nm.

Dynamics of Localized Structures in Systems with Broken Parity Symmetry.

A great variety of nonlinear dissipative systems are known to host structures having a correlation range much shorter than the size of the system. The dynamics of these localized structures (LSs) has been investigated so far in situations featuring parity symmetry. In this Letter we extend this analysis to systems lacking this property. We show that the LS drifting speed in a parameter varying landscape is not simply proportional to the parameter gradient, as found in parity preserving situations. The symmetry breaking implies a new contribution to the velocity field which is a function of the parameter value, thus leading to a new paradigm for LSs manipulation. We illustrate this general concept by studying the trajectories of the LSs found in a passively mode-locked laser operated in the localization regime. Moreover, the lack of parity affects significantly LSs interactions which are governed by asymmetrical repulsive forces.

Electrical addressing and temporal tweezing of localized pulses in passively-mode-locked semiconductor lasers

This work presents an overview of a combined experimental and theoretical analysis on the manipulation of temporal localized structures (LSs) found in passively Vertical-Cavity Surface-Emitting Lasers coupled to resonant saturable absorber mirrors. We show that the pumping current is a convenient parameter for manipulating the temporal Localized Structures, also called localized pulses. While short electrical pulses can be used for writing and erasing individual LSs, we demonstrate that a current modulation introduces a temporally evolving parameter landscape allowing to control the position and the dynamics of LSs. We show that the localized pulses drifting speed in this landscape depends almost exclusively on the local parameter value instead of depending on the landscape gradient, as shown in quasi-instantaneous media. This experimental observation is theoretically explained by the causal response time of the semiconductor carriers that occurs on an finite timescale and breaks the parity invariance along the cavity, thus leading to a new paradigm for temporal tweezing of localized pulses. Different modulation waveforms are applied for describing exhaustively this paradigm. Starting from a generic model of passive mode-locking based upon delay differential equations, we deduce the effective equations of motion for these LSs in a time-dependent current landscape

How Laser Localized Structures Evolve Out of Passive Mode-Locking

We investigate the relationship between passive mode-locking and the formation of temporal localized structures in the output of a laser, allowing for individual pulse addressing and arbitrary low repetition rates.

Phase dynamics in vertical-cavity surface-emitting lasers with delayed optical feedback and cross-polarized reinjection

We study theoretically the non linear polarization dynamics of Vertical-Cavity Surface-Emitting Lasers in the presence of an external cavity providing delayed optical feedback and cross polarization re-injection. We show that far from the laser threshold, the dynamics remains confined close to the equatorial plane of a Stokes sphere of a given radius and we reduce the dynamics to a dynamical system composed of two phases: the orientation phase of the quasi-linear polarization and the optical phase of the field. We explore the complex modal structure given by the double feedback configuration and recovers as particular cases the Lang-Kobayashi modes and the modes founds by Giudici et al. [1]. We also re-interpret the square waves switching dynamics as phase kinks.

Nonlocality Induces Chains of Nested Dissipative Solitons

Dissipative solitons often behave as quasiparticles, and they may form molecules characterized by well-defined bond distances. We show that pointwise nonlocality may lead to a new kind of molecule where bonds are not rigid. The elements of this molecule can shift mutually one with respect to the others while remaining linked together, in a manner similar to interlaced rings in a chain. We report experimental observations of these chains of nested dissipative solitons in a time-delayed laser system.

Long-tailed superthermal light as a quenching process in coupled photonic-crystal nanolasers

We experimentally and theoretically investigate the superthermal photon statistics in evanescently, strongly coupled nanolasers. The nanolasers are fabricated in suspended 2D Photonic Crystal membranes, and studied as a function of short pulse-pump power. Such a non-stationary (transient) regime leads to a new route for the generation and control of long tailed superthermal light, e.g. a light source with intensity fluctuations larger than those of thermal states. We analyze the heavy-tailed photon distributions (super-exponential) of the nonlasing (symmetric, in-phase) mode. We link, using a mean field model, both the emergence of the heavy tails and the superthermal nature of the emission. We show that passing through the lasing threshold corresponds to an abrupt decrease of the contribution of spontaneous emission - that plays the role of an effective temperature - during which the statistics of the nanolaser trajectories in phase space are dominated by transport instead of diffusion. In this sense, our photonic system can be regarded as a “quenching process”. Changing the duration of this out-of-equilibrium quenching phase, one obtains long-tailed distributions for the unstable in-phase mode in agreement with the experimental results.

Electrical addressing and temporal tweezing of localized pulses in passively mode-locked semiconductor lasers

Localized structures (LSs) in optical resonators have attracted much interest in the last twenty years. While LSs are ubiquitous in nature and their investigation conveys an intrinsic fundamental appeal, optical LSs are very attractive also for applications. Because they can be individually addressed and manipulated, LSs can be used as elementary bits of information for all-optical information processing. Recently, we have shown [1] how phase invariant temporal Localized Structures (LSs) can evolve from passive mode-locking (PML).

Nonlocality induces knotted chains of localized structures in lasers

Mechanically interlocked molecules represent chemical architectures whose composing elements are linked because of their topology instead of covalent bonds [1]. Among them, the catenanes are analogous to an ensemble of interlaced rings, globally locked yet locally independent. We disclose in this work the equivalent of such exotic molecules in the realm of nonlinear Photonics. They appear as interlocked bound states of localized structures (LSs) found in the temporal output of a Vertical-Cavity Surface-Emitting Laser (VCSEL) in presence of a point-wise nonlocality.