Fényhullámhosszon és rezgésidőn belüli skálákon szuperintenzív lézerterekben keltett legújabb nemlineáris ''attofizikai'' folyamatok elméleti és kísérleti vizsgálata. = Theoretical and experimental study of the newest nonlinear processes of ''attophysics'' generated by superintense laser fields within the light wavelength and oscillation period scale.

Számos fény-anyag kölcsönhatásra vonatkozó kísérleti vizsgálatot végeztünk el, femtoszekundumos, kevés ciklusú impulzusok által indukált fotoemisszió és felületi plazmonok által erősített elektrongyorsítás jelenségére vonatkozóan. Ezen kívül fejlesztéseket hajtottunk végre egy femtoszekundumos hosszú rezonátoros csörpölt impulzusú lézer oszcillátoron. Ez a fényforrás nagyon hasznos eszköz a fent említett kísérletekben. A elméleti kutatások során az attoszekundumos fizika, a nagy intenzitású fény-anyag kölcsönhatás és a kvantumoptika területén végezünk vizsgálatokat. A projekt során ezekből az elméleti és kísérleti témákból 19 referált nemzetközi folyóiratbeli publikáció jelent meg. | We investigated several light-matter interaction phenomena experimentally, including few-cycle pulse-induced photoemission and surface plasmon enhanced electron acceleration. We have carried out femtosecond laser development based on long-cavity, chirped-pulse laser oscillators. These sources provide very useful tools for the above mentioned experiments. In terms of theoretical studies, we investigated various field in attosecond physics, high-intensity light-matter interaction and quantum optics. These experimental and theoretical studies yielded 19 peer-reviewed journal publications during the duration of the project

Proton scattering on carbon nuclei in bichromatic laser field at moderate energies

We present the general theory for proton nuclei scattering in a bichromatic laser field. As a physical example we consider proton collision on carbon twelve at 49 MeV/amu moderate energies in the field of a titan sapphire laser with its second harmonic.Comment: 6 pages 5 figures, submitted to NIMB. arXiv admin note: text overlap with arXiv:1406.631

Carrier-envelope phase controlled isolated attosecond pulses in the nm wavelength range, based on superradiant nonlinear Thomson-backscattering

A proposal for a novel source of isolated attosecond XUV -- soft X-ray pulses with a well controlled carrier-envelope phase difference (CEP) is presented in the framework of nonlinear Thomson-backscattering. Based on the analytic solution of the Newton-Lorentz equations, the motion of a relativistic electron is calculated explicitly, for head-on collision with an intense fs laser pulse. By using the received formulae, the collective spectrum and the corresponding temporal shape of the radiation emitted by a mono-energetic electron bunch can be easily computed. For certain suitable and realistic parameters, single-cycle isolated pulses of ca. 20 as length are predicted in the XUV -- soft X-ray spectral range, including the 2.33-4.37 nm water window. According to our analysis, the generated almost linearly polarized beam is extremely well collimated around the initial velocity of the electron bunch, with considerable intensity and with its CEP locked to that of the fs laser pulse.Comment: 11 pages, 6 figures, reviewed, corrected and extended work, regarding the intensity dependence of the emitted attosecond puls

Surface plasmon assisted magnetic anomalies on room temperature gold films in high-intensity laser fields

Supplementing our STM and electron emission studies investigations, concluding in electron pairing in strong laser fields [1], further time-of-flight electron emission studies were carried out, changing the angle of polarization of the incident light, exciting surface plasmon oscillations. It has been found, that those parts of the electron spectrum which have been attributed to electron pairing have a significantly different angular dependence around 80 GW/cm2 where the pairing effect has been found than outside this region (e.g. 120 GW/cm2). These results have been interpreted as the appearance of ideal or partly ideal diamagnetism on the one hand and as anomaly in the magneto-optical effect (rotation) on the other, in the same laser intensity region where the pairing effect has been found

Reflection of a few-cycle laser pulse on a metal nano-layer: generation of phase-dependent wake-fields

The reflection and transmission of a few-cycle femtosecond Ti:Sa laser pulse impinging on a metal nano-layer have been analysed. The thickness of the layer was assumed to be of order of 2-10 nm, and the metallic free electrons were represented by a surface current density distributed at the plane boundary of a dielectric substrate. The target studied this way can be imagined, for instance, as a semi-transparent mirror produced by evapotating a thin aluminum layer on the surface of a glass plate. The exact analytic solution has been given for the system of the coupled Maxwell-Lorentz equations decribing the dynamics of the surface current and the scattered radiation fields. It has been shown that in general a non-oscillatoty frozen-in wake-field appears following the main pulse with an exponential decay and with a definite sign of the electric field. The characteristic time of these wake-fields is inversely proportional with the square of the plasma frequency and with the thickness of the metal nano-layer, and can be larger than the original pulse duration. The magnitude of these wake-fields is proportional with the incoming field strength, and the definite sign of them governed by the cosine of the carrier-envelope phase difference of the incoming ultrashort laser pulse. As a consequence, when we let such a wake-field excite the electrons of a secondary target (say an electron beam, a metal plate or a gas jet), we obtain 100 percent modulation in the electron signal in a given direction, as we vary the carrier-envelope phase difference. This scheeme can perhaps serve as a basis for the construction of a robust linear carrier-envelope phase difference meter.Comment: 8 pages, 2 figure

Generic Search Plans for Matching Advanced Graph Patterns

In the current paper, we present search plans which can guide pattern matching for advanced graph patterns with edge identities, containment constraints, type variables, negative application conditions, attribute conditions, and injectivity constraints. Based on a generic search graph representation, all search plan operations (e.g. checking the existence of an edge, or extending a matching candidate by navigating along an edge) are uniformly represented as special predicates with heuristically assigned costs. Finally, an executable search plan is defined as an appropriate ordering of these predicates. As a main consequence, attribute, injectivity, and negative application conditions can be checked early (but not unnecessarily early) in the pattern matching process to cut off infeasible matching candidates at the right time

Designing the automatic transformation of visual languages

AbstractThe design process of complex systems requires a precise checking of the functional and dependability attributes of the target design. The growing complexity of systems necessitates the use of formal methods, as the exhaustiveness of checks performed by the traditional simulation and testing is insufficient.For this reason, the mathematical models of various formal verification tools are automatically derived from UML-diagrams of the model by mathematical transformations guaranteeing a complete consistency between the target design and the models of verification and validation tools.In the current paper, a general framework for an automated model transformation system is presented. The method starts from a uniform visual description and a formal proof concept of the particular transformations by integrating the powerful computational paradigm of graph transformation, planner algorithms of artificial intelligence, and various concepts of computer engineering

Laser induced distortion of band structure in solids: an analytic model

We consider a spatially periodic (cosine) potential as a model for a crystalline solid that interacts with a harmonically oscillating external electric field. This problem is periodic both in space and time and can be solved analytically using the Kramers-Henneberger co-moving frame. By analyzing the stability of the closely related Mathieu-type differential equation, the electronic band structure can be obtained. We demonstrate that by changing the field intensity, the width of the zero-field band gaps can be drastically modified, including the special case when the external field causes the band gaps to disappearComment: 8 pages, 3 figure

Incremental Graph Pattern Matching: Data Structures and Initial Experiments

Despite the large variety of existing graph transformation tools, the implementation of their pattern matching engine typically follows the same principle. First a matching occurrence of the left-hand side of the graph transformation rule is searched by some graph pattern matching algorithm. Then potential negative application conditions are checked that might eliminate the previous occurrence. However, when a new transformation step is started, all the information on previous matchings is lost, and the complex graph pattern matching phase is restarted from scratch each time. In the paper, we present the foundational data structures and initial experiments for an incremental graph pattern matching engine which keeps track of existing matchings in an incremental way to reduce the execution time of graph pattern matching