Fine interference fringes formed in high-order harmonic spectra generated by infrared driving laser pulses

We experimentally investigate the high-order harmonic generation in argon gas using a driving laser pulse at a center wavelength of 1240 nm. High-contrast fine interference fringes could be observed in the harmonic spectra near the propagation axis, which is attributed to the interference between long and short quantum paths. We also systematically examine the variation of the interference fringe pattern with increasing energy of the driving pulse and with different phase-matching conditions.

La influencia del uso de dispositivos móviles en la tienda en la experiencia de compra e intención de compra de los consumidores

Máster en Dirección Empresarial desde la Innovación y la Internacionalización. Curso 2013/2014

Formation of X-waves at fundamental and harmonics by infrared femtosecond pulse filamentation in air

We experimentally observe the formation of X-waves at fundamental, third harmonic, and fifth harmonic wavelengths by infrared (central wavelength at similar to 1500 nm) femtosecond laser pulse filamentation in air. By fitting the angularly resolved spectra of the fundamental and harmonic waves using X-wave relations, we confirm that all the X-waves have nearly the same group velocity, indicating that they are locked in space and time during their propagation in filament.

Laser intensity dependence of high-order harmonic generation from aligned CO2 molecules

We investigate experimentally the high-order harmonic generation from aligned CO2 molecules and demonstrate that the modulation inversion of the harmonic yield with respect to molecular alignment can be altered dramatically by fine-tuning the intensity of the driving laser pulse for harmonic generation. The results can be modeled by employing the strong field approximation including a ground state depletion factor. The laser intensity is thus proved to be a parameter that can control the high-harmonic emission from aligned molecules.

Autismoa literaturan

[EUS]Lan hau nik asmaturiko ipuin baten egokitzapenean oinarritzen da, eta horretarako erabili ditudan materialen ezberdinen deskribapena egiten dut. Lan hau egin dut autismoa daukaten haurrek besteak bezalakoak direlako eta eskubide berdinak dituztelako. Beraz, irakasleak jakitea zein izan behar den autismoa daukaten haurrei eman behar dien erantzun egokia garrantzitsua da, batez ere, haurren ulermena eta komunikazioa hobetzeko. Ondorioz, gainontzeko haurrekin erlazionatzeko eta autonomoagoak izateko aukera izango dute. Oso garrantzitsua da gogoratzea haur bakoitza ezberdina dela, eta edozein egokitzapena egiterako orduan, bakoitzaren ezaugarriak, beharrak eta gaitasunak hartu behar dira kontutan.

Spectral evolution of angularly resolved third-order harmonic generation by infrared femtosecond laser-pulse filamentation in air

We experimentally investigate the evolution of an angularly resolved spectrum of third harmonic generated by infrared femtosecond laser pulse filamentation in air. We show that at low pump intensity, phase matching between the fundamental and third-harmonic waves dominates the nonlinear optical effect and induces a ring structure of the third-harmonic beam, whereas at high pump intensity, the dispersion properties of air begin to affect the angular spectrum, leading to the formation of a nonlinear X wave at third harmonic.

X-shaped third harmonic generated by ultrashort infrared pulse filamentation in air

The authors report the measurement of the angularly resolved spectrum of the third harmonic generated in a femtosecond filament in air and its evolution with increasing pump power. Pumped by a focused infrared ultrashort pulse with a carrier wavelength of 1270 nm, a pulse duration of similar to 20 fs, and pulse energy up to 487 mu J, the generated third harmonic is composed of an on-axis emission and a conical ring emission. When the pump power is sufficiently high, angularly resolved spectra with significant X-like feature could be observed, indicating the formation of nonlinear X wave at third harmonic. (c) 2008 American Institute of Physics.

Single sub-100 attosecond pulse generation in a two-colour time-gating laser field

We theoretically propose a method of generating a single sub-100 attosecond (as) pulse with a two-colour time-gating laser field. The field is synthesized by an 8 fs/800 nm (three optical cycles) pulse and a 24 fs/2400 nm (three optical cycles) pulse with an optimal time delay between them. In our simulation, we obtain a supercontinuum with an extremely broad spectrum of 150 eV and generate an isolated attosecond pulse with 96 as pulse duration without any dispersion compensation.

Phase-matched high-order harmonic generation in a gas cell with midinfrared femtosecond pulses

We experimentally investigate the generation of high-order harmonics in a 4-mm-long gas cell using midinfrared femtosecond pulses at various wavelengths of 1240 nm, 1500 nm, and 1800 nm. It is observed that the yield and cutoff energy of the generated high-order harmonics critically depend on focal position, gas pressure, and size of the input beam which can be controlled by an aperture placed in front of the focal lens. By optimizing the experimental parameters, we achieve a cutoff energy at similar to 190 eV with the 1500 nm driving pulses, which is the highest for the three wavelengths chosen in our experiment.

Irakaslearen ikuspegi psikopedagogikoaren eragina idazketa prozesuaren hastapenetan: Avellaneda, Etorkizuna eta Eguzkibegi ikastetxeetako kasuen azterketa

EUSKARA LABURPENA:Haurrek hizkuntza idatzia nola barneratzen duten eta irakasteko metodorik egokiena zein izan daitekeen inguruko eztabaida egon izan da aspalditik. Gai horri buruz, haurrek idazketaz egiten duten jabekuntza prozesuan irakasleen ikuspegi psikopedagogikoek zer nolako eragina duten haurrengan ikertu dugu. Ikerketaren alde kualitatibo eta kuantitatiboei erreparatuz, metodologia berritzaileen aplikazio ezberdinak egiten dituzten Bizkaiko Avellaneda, Etorkizuna eta Eguzkibegi ikastetxeetan ikerketa sinkroniko bat eraman dugu aurrera. Lanerako lagina HHko etapako 5 urteko gelan dauden 55 ikaslek eta 6 irakaslek osatu dute. Emaitzek adierazten dutenez, ikuspegi tradizionalean heziak dauden haurrek idazkeraren alde figuratiboekiko ziurtasun handiagoa erakusten dute eta eredu eraikitzailean hezitakoek, berriz, komunikazio gaitasun handiagoa dute. Eredu bakoitzak bere indar-guneak eta ahulguneak izateak zaildu egiten du eredu baten egokitasuna nabarmentzea.

Temporal confinement and enhancement of high-order harmonic emission with a synthesized laser field

We demonstrated that a synthesized laser field consisting of an intense long (45 fs, multi-optical-cycle) laser pulse and a weak short (7 fs, few-optical-cycle) laser pulse can control the electron dynamics and high-order harmonic generation in argon, and generate extreme ultraviolet supercontinuum towards the production of a single strong attosecond pulse. The long pulse offers a large amplitude field, and the short pulse creates a temporally narrow enhancement of the laser field and a gate for the highest energy harmonic emission. This scheme paves the way to generate intense isolated attosecond pulses with strong multi-optical-cycle laser pulses.

Análisis de sensibilidad en los procedimientos de calibración de robots de cinemática paralela Aplicación al mecanismo 5R

[ES]Este proyecto investigador tiene como objetivo el ayudar con la calibración del mecanismo de cinco pares de rotación montado en el taller de Ingeniería Mecánica de la ETSI de Bilbao. En primer lugar se estudiarán los algoritmos de optimización prestando especial atención a la comparativa entre Levenberg-Marquart y Gauss-Newton. Se realizarán estudios en Matlab para concluir cuál de los dos es más eficaz tanto en rapidez como en precisión. El que sea más adecuado se implementará en un programa para la calibración del mecanismo 5R. En segundo lugar se estudiarán los índices de observabilidad. Los estudios que se han realizado sobre ellos hasta ahora son poco concluyentes asique se intentará aclarar su utilidad y determinar cuál es el que conviene utilizar en este caso. Para ello se deberá programar la resolución del problema cinemático inverso. Por último se presentarán los resultados y las conclusiones correspondientes. Se propondrá también un plan de desarrollo de una línea de investigación futura que partirá con este trabajo como base.

Estudio comparativo de diferentes soluciones de fachada y cubierta para un edificio residencial

[ES]En el proyecto se analizan diferentes soluciones de fachada y cubierta de un edificio residencial, buscando la eficiencia energética y la economía. Para ello, partiendo de un caso concreto, se estudian las cargas térmicas del edificio existente y de otras dos soluciones posibles. En estas además, se utilizan materiales sostenibles, con el fin de hacer el menor impacto medioambiental posible. Se ha analizado también la rentabilidad de estas soluciones, para comprobar cuál es la más adecuada desde un punto de vista económico.