Arrays of coupled semiconductor lasers are systems possessing radically complex dynamics that makes them useful for numerous applications in beam forming and beam shaping. In this work, we investigate the spatial controllability of oscillation amplitudes in an array of coupled photonic dimers, each consisting of two semiconductor lasers driven by differential pumping rates. We consider parameter values for which each dimer's stable phase-locked state has become unstable through a Hopf bifurcation and we show that, by assigning appropriate pumping rate values to each dimer, large-amplitude oscillations coexist with negligibly small amplitude oscillations. The spatial profile? of the amplitude of oscillations across the array can be dynamically controlled by appropriate pumping rate values in each dimer. This feature is shown to be quite robust, even for random detuning between the lasers, and suggests a mechanism for dynamically reconfigurable production of a large diversity of spatial profiles of laser amplitude oscillations.
Rubidium dimers residing on the surface of He nanodroplets are doubly ionized by an intense fs laser pulse leading to fragmentation into a pair of $\mathrm{Rb^+}$ ions. We show that the kinetic energy of the $\mathrm{Rb^+}$ fragment ions can be used to identify dimers formed in either the X $^1Σ_{\mathrm{g}}^+$ ground state or in the lowest-lying triplet state, a $^3Σ_{\mathrm{u}}^+$. From the experiment, we estimate the abundance ratio of dimers in the a and X states as a function of the mean droplet size and find values between 4:1 and 5:1. Our technique applies generally to dimers and trime…
Asymmetric metal-dielectric nanostructures are demonstrated superior optical properties arise from the combination of strong enhancement of their near fields and controllable scattering characteristics which originate from plasmonic and high-index dielectric components. Here, being inspired by the recent experimental work [Dmitry~Zuev, \textit{et al.}, Adv. Mater. \textbf{28}, 3087 (2016)] on a new technique for fabrication of asymmetric hybrid nanoparticles via femtosecond laser melting at the nanoscale, we suggest and study numerically a novel type of hybrid dimer nanoantennas. The nanoanten…
Coupled semiconductor lasers are systems possessing complex dynamics that are interesting for numerous applications in photonics. In this work, we investigate the existence and the stability of asymmetric phase-locked states of the fundamental active photonic dimer consisting of two coupled lasers. We show that stable phase-locked states of arbitrary asymmetry exist for extended regions of the parameter space of the system and that their field amplitude ratio and phase difference can be dynamically controlled by appropriate current injection. The model includes the important role of carrier de…
We experimentally investigate the nonlinear dynamics of two coupled fiber ring resonators, coherently driven by a single laser beam. We comprehensively explore the optical switching arising when scanning the detuning of the undriven cavity, and show how the driven cavity detuning dramatically changes the resulting hysteresis cycle. By driving the photonic dimer out-of-equilibrium, we observe the occurrence of stable self-switching oscillations near avoided resonance crossings. All results agree well with the driven-dissipative Bose-Hubbard dimer model in the weakly coupled regime.
We have deduced the structure of the \ce{bromobenzene}--\ce{I2} heterodimer and the \ce{(bromobenzene)2} homodimer inside helium droplets using a combination of laser-induced alignment, Coulomb explosion imaging, and three-dimensional ion imaging. The complexes were fixed in a variety of orientations in the laboratory frame, then in each case multiply ionized by an intense laser pulse. A three dimensional ion imaging detector, including a Timepix3 detector allowed us to measure the correlations between velocity vectors of different fragments and, in conjunction with classical simulations, work…
We show that the pumping current is a convenient parameter for manipulating the temporal Localized Structures (LSs), also called localized pulses, found in passively mode-locked Vertical-Cavity Surface-Emitting Lasers. 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 …
We investigate a control of the motion of localized structures of light by means of delay feedback in the transverse section of a broad area nonlinear optical system. The delayed feedback is found to induce a spontaneous motion of a solitary localized structure that is stationary and stable in the absence of feedback. We focus our analysis on an experimentally relevant system namely the Vertical-Cavity Surface-Emitting Laser (VCSEL). In the absence of the delay feedback we present experimental evidence of stationary localized structures in a 80 $μ$m aperture VCSEL. The spontaneous formation of…
In sufficiently strong scattering media, light transport is suppressed and modes are exponentially localized. Anderson-like localized states have long been recognized as potential candidate for high-Q optical modes for low-threshold, cost effective random lasers. Operating in this regime remains however a challenge since Anderson localization is difficult to achieve in optics and nonlinear mode interaction compromise its observation. Here, we exhibit individually each lasing mode of a low-dimension solid-state random laser by applying a non-uniform optical gain. By undoing gain competition and…
We analyze the emergence of wiggling temporal localized states in a passively mode-locked Vertical External- Cavity Surface-Emitting Laser composed by a gain chip and a resonant saturable absorber mirror. We show that the wiggling instability stems from the interplay between the third-order dispersion induced by the micro-cavities and their frequency mismatch. The latter is identified as an experimentally crucial parameter defining the range of existence of stable emission. We reveal the homoclinic scenario underlying the wiggling phenomenon and we show how it allows to control the oscillation…
In this paper, we analyze the effect of optical feedback on the dynamics of a passively mode-locked ring laser operating in the regime of temporal localized structures. This laser system is modeled by a system of delay differential equations, which include delay terms associated with the laser cavity and the feedback loop. Using a combination of direct numerical simulations and path-continuation techniques, we show that the feedback loop creates echos of the main pulse whose position and size strongly depend on the feedback parameters. We demonstrate that in the long-cavity regime, these echos…
We demonstrate low-threshold random lasing in random amplifying layered medium via photon localization. Lasing is facilitated by resonant excitation of localized modes at the pump laser wavelength, which are peaked deep within the sample with greatly enhanced intensity. Emission occurs into long-lived localized modes overlapping the localized gain region. This mechanism overcomes a fundamental barrier to reducing lasing thresholds in diffusive random lasers, in which multiple scattering restricts the excitation region to the proximity of the sample surface.
Temporal Localized States (TLSs) are individually addressable structures traveling in optical resonators. They can be used as bits of information and to generate frequency combs with tunable spectral density. We show that a pair of specially designed nonlinear mirrors, a 1/2 Vertical-Cavity Surface-Emitting Laser and a Semiconductor Saturable Absorber, coupled in self-imaging conditions, can lead to the generation of such TLSs. Our results indicate how a conventional passive mode- locking scheme can be adapted to provide a robust and simple system emitting TLSs and it paves the way towards the…
We show experimentally and theoretically that localized pulses can be generated from an electrically biased $200\,μ$m multi-transverse mode Vertical-Cavity Surface-Emitting Laser. The device is passively mode-locked using optical feedback from a distant Resonant Saturable Absorber Mirror and it is operated below threshold. We observe multistability between the off solution and a large variety of pulsating solutions with different number and arrangements of pulses per round-trip, thus indicating that the mode-locked pulses are localized, i.e. mutually independent. We show that a modulation of t…
The fundamental active photonic dimer consisting of two coupled quantum well lasers is investigated in the context of the rate equation model. Spectral transition properties and exceptional points are shown to occur under general conditions, not restricted by PT-symmetry as in coupled mode models, suggesting a paradigm shift in the field of non-Hermitian photonics. The optical spectral signatures of system bifurcations and exceptional points are manifested in terms of self-termination effects and observable drastic variations of the spectral line shape that can be controlled in terms of optica…
High-power femtosecond laser radiation propagates nonlinearly in air exhibiting pulse self-focusing and strong multiphoton medium ionization, which leads to the spatial fragmentation of laser pulse into highly-localized light channels usually called the filaments. The filaments are characterized by high optical intensity, reduced (even zero) angular spreading and can contain laser plasma or be plasmaless (postfilaments). The presence of optical turbulence on the propagation path dramatically changes pulse filamentation dynamics and in some cases causes pulse fragmentation enhancement and colla…
Understanding random lasing is a formidable theoretical challenge. Unlike conventional lasers, random lasers have no resonator to trap light, they are highly multimode with potentially strong modal interactions and they are based on disordered gain media, where photons undergo random multiple scattering. Interference effects notoriously modify the propagation of waves in such random media, but their fate in the presence of nonlinearity and interactions is poorly understood. Here, we present a semiclassical theory for multimode random lasing in the strongly scattering regime. We show that Ander…
We analyze how a star network topology shapes the dynamics of coupled CO\textsubscript{2} lasers with an intracavity electro-optic modulator that exhibit bistability. Such a network supports spreading and stationary activation patterns. In particular, we observe an activation spreading where the activated periphery turns on the center element, an activated center which drifts the periphery into the active region and an activation of the whole system from the passive into the active region. Pinned activation, namely activation localized only in the center or the peripheral elements is also foun…
Among hundreds of impurities and defects in diamond, the nitrogen-vacancy (NV) center is one of the most interesting to be used as a platform for quantum technologies and nanosensing. Traditionally, synthetic diamond is irradiated with high-energy electrons or nitrogen ions to generate these color-centers. For precise positioning of the NV centers, fs-laser irradiation has been proposed as an alternative approach to produce spatially localized NV centers in diamond. However, most of the studies reported so far used high-repetition rate fs-laser systems. Here, we studied the influence of the ir…
Optical localized states are usually defined as self-localized bistable packets of light which exist as independently controllable optical intensity pulses either in the longitudinal or transverse dimension of nonlinear optical systems. Here we provide the first experimental and analytical demonstration of the existence of longitudinal localized states which exist fundamentally in the phase of laser light. These robust and versatile phase bits can be individually nucleated and canceled in an injection-locked semiconductor laser operated in a neuron- like excitable regime and submitted to delay…
We study the emergence and the stability of temporal localized structures in the output of a semiconductor laser passively mode-locked by a saturable absorber in the long cavity regime. For large yet realistic values of the linewidth enhancement factor, we disclose the existence of secondary dynamical instabilities where the pulses develop regular and subsequent irregular temporal oscil- lations. By a detailed bifurcation analysis we show that additional solution branches that consist in multi-pulse (molecules) solutions exist. We demonstrate that the various solution curves for the single and…
Anderson localization lasers exploit resonant cavities formed due to structural disorder. The inherent randomness in the structure of these cavities realizes a probability distribution in all cavity parameters such as quality factors, mode volumes, mode structures etc, implying resultant statistical fluctuations in the temporal behavior. Here, we provide the first, direct experimental measurements of temporal width distributions of Anderson localization lasing pulses in intrinsically and extrinsically disordered coupled-microresonator arrays. We first illustrate signature exponential decays in…
Controlling the near field optical binding force can be a key factor for particle clustering, aggregation and localized surface plasmon sensors. So far there is no generic way to reverse the near field optical binding force for plasmonic or dielectric nano-dimers of distinct shapes (cube, cylinder, ring, sphere). In this article, for both plasmonic and dielectric objects, we have demonstrated a general way to control the reversal of near field binding force for different shaped dimer sets. The force reversal is achieved by simple breaking of symmetry, considering the nano particles are half or…
The evidence of strong coupling between plasmons and molecular excitons for plasmonic nanoparticle (NP) dimers exhibiting ultra-sensitive surface enhanced resonant Raman scattering is the observation of anti-crossing in the coupled resonance. However, it is not easy to experimentally tune plasmon resonance of such dimers for the observation. In this work, we theoretically investigate the anti-crossing properties of the dimers coated by the thin dye films with thicknesses greater than 0.1 nm and gap distances larger than 1.2 nm according to the principles of classical electromagnetism. The plas…
Ultrabroad resonance of localized plasmon on a nanoparticle coupled with surface plasmon on a nanowire enabling two-photon excited emission via continuous-wave laser
Localized crystallization of Ce:YIG thin films on Si using CO2 laser annealing for integrated nonreciprocal photonic device applications
National Engineering Research Centre of Electromagnetic Radiation Control Materials, University of Electronic Science and Technology of China（电磁辐射控制材料工程技术研究中心，电子科技大学）；State Key Laboratory of Electronic Thin-Films and Integrated Devices, University of Electronic Science and Technology of China（电子薄膜与集成器件国家重点实验室，电子科技大学）
