1,721,071 research outputs found
3D cavity light bullets in a nonlinear optical resonator
No full textWe consider a nonlinear ring cavity resonator filled by a saturable absorber and driven by a plane wave field. Under the slowly varying envelope and paraxial approximation, we introduce a quite general approach to the analysis of the spatio-temporal dynamics of the coherent field beyond the mean-field limit, fully taking into account propagation, diffraction and the boundary conditions imposed by the cavity. We study the stability of the stationary solutions versus spatially modulated perturbations, and identify regimes where we observe total radiation confinement and the formation of 3D localised bright structures. At difference from freely propagating light bullets, here the self-organization proceeds from the combination of difrraction, nonlinearity and resonator feedback. Such cavity light bullets (CLBs) endlessly travel the cavity roundtrip and can be independently manipulated. These characteristics makes CLBs natural candidates for optical bits and for particle-like optical probes
Three-dimensional self-organized patterns in the field profile of a ring cavity resonator
No full textWe consider the paraxial model for a nonlinear resonator filled with a saturable absorber, beyond the mean field limit. We develop a general treatment to study the modulational instabilities which give rise to pattern formation in the propagation direction z and in the transverse plane (x, y). For appropriate parametric domains we observe the first example of system self-organization in space and time proceeding from competition of linear effects with nonlinear medium properties and resonator feedback. In particular, we could observe either 3D global structures or structures which are localized in the transverse plane, showing different lengths in the longitudinal direction and endlessly travelling in the resonator
Modulation properties and nonlinear dynamics induced by optical feedback in distributed-feedback quantum cascade lasers
Full text linkThis study explores the dynamic behavior of distributed-feedback quantum cascade lasers (QCLs) through numerical simulations based on the Effective Semiconductor Maxwell-Bloch Equations (ESMBEs). First, we analyze the intrinsic intensity modulation response of QCLs, demonstrating that the modulation bandwidth is fundamentally constrained by the population grating induced by the standing-wave pattern in the QCL cavity, namely, spatial hole burning (SHB). We then extend the ESMBEs framework to incorporate the effects of an external target, enabling the investigation of multimode nonlinear dynamics in QCLs subject to external optical feedback (EOF). Our findings identify fast SHB and a non-zero linewidth enhancement factor as key physical mechanisms governing the emergence of complex multimode behavior and the eventual transition to chaos. Notably, we reveal that QCL destabilization under EOF arises from interactions between internal longitudinal modes and external cavity modes, rather than from undamped relaxation oscillations, as typically observed in conventional semiconductor lasers. Furthermore, we examine the evolution of the system's dynamics as a function of feedback strength, demonstrating the onset of photonic chaos at feedback levels two orders of magnitude higher than those required in traditional diode lasers, in agreement with experimental observations existing in the literature. Finally, we assess the correlation dimension of the attractor of the resulting nonlinear dynamics. Beyond fundamental insight, this work introduces the use of ESMBEs as a predictive framework for experimental interpretation and device design, enabling the engineering of QCLs for mid- and long-infrared free-space applications, including high-speed transmission, chaos-based LiDAR, and random number generation. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International (CC BY-NC-ND) license (https://creativecommons.org/licenses/by-nc-nd/4.0/)
On homoclinic snaking in optical systems
No full textThe existence of localized structures, including so-called cavity solitons, in driven optical systems is discussed. In theory, they should exist only below the threshold of a subcritical modulational instability, but in experiment they often appear spontaneously on parameter variation. The addition of a nonlocal nonlinearity may resolve this discrepancy by tilting the "snaking" bifurcation diagram characteristic of such problems. (c) 2007 American Institute of Physics
Cavity Light Bullets: Three-Dimensional Localized Structures in a Nonlinear Optical Resonator
No full textThe paraxial model for a nonlinear resonator with a saturable absorber beyond the meanfield limit was investigated. Total radiation confinement and the formation of 3D localized bright structures was observed for accessible parametric domains. It was observed that self-organization proceeded from the resonator feedback, combined with diffraction and nonlinearity. Analysis shows that light bullets can be independently excited and erased by appropriate pulses, and after creation they endlessly travel the cavity round-trip
Self-mixing in multi-transverse mode semiconductor lasers: model and potential application to multi-parametric sensing
No full textA general model is proposed for a Vertical Cavity Surface Emitting Laser (VCSEL) with medium aspect ratio whose field profile can be described by a limited set of Gauss-Laguerre modes. The model is adapted to self-mixing schemes by supposing that the output beam is reinjected into the laser cavity by an external target mirror. We show that the self-mixing interferometric signal exhibits features peculiar of the spatial distribution of the emitted field and the target-reflected field and we suggest an applicative scheme that could be exploited for experimental displacement measurements. In particular, regimes of transverse mode-locking are found, where we propose an operational scheme for a sensor that can be used to simultaneously measure independent components of the target displacement like target translations along the optical axis (longitudinal axis) and target rotations in a plane orthogonal to the optical axis (transverse plane). (C) 2012 Optical Society of Americ
Laser Optical Feedback Turns 60
Full text linkAs soon as a laser is fired, some of the emitted light is scattered backward and coupled with the cavity modes, causing instability. However, already in March 1962, Kleinman and Kisliuk [1] suggested that controlled back reflection from an external mirror could help the stabilization of the fundamental cavity mode by suppressing the higher-order ones. Soon afterward, King and Steward [2] proposed the exploitation of optical feedback for metrology, and laser self-mixing (LSM) eventually became an established research topic. Sixty years and a few thousand publications later, this Special Issue celebrates some of the most recent achievements in optical feedback interferometry (OFI), as LSM is currently addressed.
The Special Issue includes four research articles, each covering one aspect of the multivariate system simply consisting of a laser and a scattering target. These papers relate to modeling new type of lasers, implementing commercial applications, and deepening our understanding of laser dynamics
Terahertz active spatial filtering through optically tunable hyperbolic metamaterials
No full textWe theoretically consider infrared-driven hyperbolic metamaterials able to spatially filter terahertz (THz) radiation. The metamaterial is a slab made of alternating semiconductor and dielectric layers whose homogenized uniaxial response, at THz frequencies, shows principal permittivities of different signs. The gap provided by metamaterial hyperbolic dispersion allows the slab to stop spatial frequencies within a bandwidth tunable by changing the infrared radiation intensity. We numerically prove the device functionality by resorting to full wave simulation coupled to the dynamics of charge carries photoexcited by infrared radiation in semiconductor layers. (C) 2012 Optical Society of Americ
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