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- ItemFemtosecond Field‐Driven On‐Chip Unidirectional Electronic Currents in Nonadiabatic Tunneling Regime(Weinheim : Wiley VCH, 2021) Shi, Liping; Babushkin, Ihar; Husakou, Anton; Melchert, Oliver; Frank, Bettina; Yi, Juemin; Wetzel, Gustav; Demircan, Ayhan; Lienau, Christoph; Giessen, Harald; Ivanov, Misha; Morgner, Uwe; Kovacev, MilutinRecently, asymmetric plasmonic nanojunctions have shown promise as on-chip electronic devices to convert femtosecond optical pulses to current bursts, with a bandwidth of multi-terahertz scale, although yet at low temperatures and pressures. Such nanoscale devices are of great interest for novel ultrafast electronics and opto-electronic applications. Here, the device is operated in air and at room temperature, revealing the mechanisms of photoemission from plasmonic nanojunctions, and the fundamental limitations on the speed of optical-to-electronic conversion. Inter-cycle interference of coherent electronic wavepackets results in a complex energy electron distribution and birth of multiphoton effects. This energy structure, as well as reshaping of the wavepackets during their propagation from one tip to the other, determine the ultrafast dynamics of the current. It is shown that, up to some level of approximation, the electron flight time is well-determined by the mean ponderomotive velocity in the driving field.
- ItemStability of quantum linear logic circuits against perturbations(Bristol : IOP Publ., 2020) Babushkin, Ihar; Morgner, Uwe; Demircan, AyhanHere we study transformation of waveshapes of photons under the action of the linear logic circuits and other related architectures involving only linear optical networks and measurements. We show that the gates are working well not only in the case when all photons are separable and located in the same mode, but in some more general cases. For instance, the photonic waveshapes are allowed to be slightly different in different channels; in this case, Zeno effect prevents the photons from decoherence after the measurement, and the gate thus remains neutral to the small waveshape perturbations. © 2020 The Author(s). Published by IOP Publishing Ltd Printed in the UK
- ItemThe Effect of Chirp on Pulse Compression at a Group Velocity Horizon(New York, NY : IEEE, 2016) Babushkin, Ihar; Amiranashvili, Shalva; Bree, Carsten; Morgner, Uwe; Steinmeyer, Gunter; Demircan, AyhanGroup-velocity matched cross-phase modulation between a fundamental soliton and a dispersive wave packet has been previously suggested for optical switching applications similar to an optical transistor. Moreover, the nonlinear interaction in the resulting group-velocity horizon can be exploited for adiabatic compression of the soliton down into the few-cycle regime. Here, we study the delicate phase- and frequency-matching mechanism of soliton/dispersive wave interaction by controlling the input chirp of the dispersive wave. We demonstrate that such a modification of the dispersive wave can significantly alter the soliton dynamics. In particular, we show that it allows a decrease of the fiber length needed for the best compression and, to some extent, control of the trajectory of the soliton. The mechanism of such an influence is related to the modification of the phase-matching condition between the soliton and dispersive wave.
- ItemAll-optical supercontinuum switching(London : Springer Nature, 2020) Melchert, Oliver; Brée, Carsten; Tajalli, Ayhan; Pape, Alexander; Arkhipov, Rostislav; Willms, Stephanie; Babushkin, Ihar; Skryabin, Dmitry; Steinmeyer, Günter; Morgner, Uwe; Demircan, AyhanEfficient all-optical switching is a challenging task as photons are bosons and cannot immediately interact with each other. Consequently, one has to resort to nonlinear optical interactions, with the Kerr gate being the classical example. However, the latter requires strong pulses to switch weaker ones. Numerous approaches have been investigated to overcome the resulting lack of fan-out capability of all-optical switches, most of which relied on types of resonant enhancement of light-matter interaction. Here we experimentally demonstrate a novel approach that utilizes switching between different portions of soliton fission induced supercontinua, exploiting an optical event horizon. This concept enables a high switching efficiency and contrast in a dissipation free setting. Our approach enables fan-out, does not require critical biasing, and is at least partially cascadable. Controlling complex soliton dynamics paves the way towards building all-optical logic gates with advanced functionalities. © 2020, The Author(s).
- ItemOcean rogue waves and their phase space dynamics in the limit of a linear interference model(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2016) Birkholz, Simon; Brée, Carsten; Veselic, Ivan; Demircan, Ayhan; Steinmeyer, GünterWe reanalyse the probability for formation of extreme waves using the simple model of linear interference of a finite number of elementary waves with fixed amplitude and random phase fluctuations. Under these formation becomes increasingly likely, with appearance frequencies that may even exceed long-term observations by an order of magnitude. For estimation of the effective number of interfering waves, we suggest the Grassberger-Procaccia dimensional analysis of individual time series. For the ocean system, it is further shown that the resulting phase space dimension may vary, such that the threshold for rogue wave formation is not always reached. Time series analysis as well as the appearance of particular focusing wind conditions may enable an effective forecast of such rogue-wave prone situations. In particular, extracting the dimension from ocean time series allows much more specific estimation of the rogue wave probability.
- ItemAccelerated rogue solitons triggered by background radiation(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2015) Demircan, Ayhan; Amiranashvili, Shalva; Brée, Carsten; Morgner, Uwe; Steinmeyer, Günter[no abstract available]
- ItemSymmetry breaking and strong persistent plasma currents via resonant destabilization of atoms(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2017) Brée, Carsten; Hofmann, Michael; Babushkin, Ihar; Demircan, Ayhan; Morgner, Uwe; Kosareva, Olga G.; Savelev, Andrei B.; Husakou, Anton; Ivanov, MishaThe ionization rate of an atom in a strong optical field can be resonantly enhanced by the presence of long-living atomic levels (so called Freeman resonances). This process is most prominent in the multiphoton ionization regime meaning that ionization event takes many optical cycles. Nevertheless, here we show that these resonances can lead to fast subcycle-scale plasma buildup at the resonant values of the intensity in the pump pulse. The fast buildup can break the cycletocycle symmetry of the ionization process, resulting in generation of persistent macroscopic plasma currents which remain after the end of the pulse. This, in turn, gives rise to a broadband radiation of unusual spectral structure forming a comb from terahertz (THz) to visible. This radiation contains fingerprints of the attosecond electronic dynamics in Rydberg states during ionization.
- ItemAdjustable pulse compression scheme for generation of few-cycle pulses in the mid-infrared(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2014) Demircan, Ayhan; Amiranashvili, Shalva; Brée, Carsten; Morgner, Uwe; Steinmeyer, GünterAn novel adjustable adiabatic soliton compression scheme is presented, enabling a coherent pulse source with pedestal-free few-cycle pulses in the infrared or mid-infrared regime. This scheme relies on interaction of a dispersive wave and a soliton copropagating at nearly identical group velocities in a fiber with enhanced infrared transmission. The compression is achieved directly in one stage, without necessity of an external compensation scheme. Numerical simulations are employed to demonstrate this scheme for silica and fluoride fibers, indicating ultimate limitations as well as the possibility of compression down to the single-cycle regime. Such output pulses appear ideally suited as seed sources for parametric amplification schemes in the mid-infrared.
- ItemSupercontinuum generation by multiple scatterings at a group velocity horizon(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2014) Demircan, Ayhan; Amiranashvli, Shalva; Brée, Carsten; Morgner, Uwe; Steinmeyer, GünterA new scheme for supercontinuum generation covering more than one octave and exhibiting extraordinary high coherence properties has recently been proposed in Phys. Rev. Lett. 110, 233901 (2013). The scheme is based on two-pulse collision at a group velocity horizon between a dispersive wave and a soliton. Here we demonstrate that the same scheme can be exploited for the generation of supercontinua encompassing the entire transparency region of fused silica, ranging from 300 to 2300nm. At this bandwidth extension, the Raman effect becomes detrimental, yet may be compensated by using a cascaded collision process. Consequently, the high degree of coherence does not degrade even in this extreme scenario.
- ItemSelf-compression of 120 fs pulses in a white-light filament(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2010) Bethge, Jens; Steinmeyer, Günter; Stibenz, Gero; Staudt, Peter; Brée, Carsten; Demircan, Ayhan; Redlin, Harald; Düsterer, StefanSelf-compression of pulses with >100 fs input pulse duration from a 10 Hz laser system is experimentally demonstrated, with a compression factor of 3.3 resulting in output pulse durations of 35 fs. This measurement substantially widens the range of applicability of this compression method, enabling self-compression of pulsed laser sources that neither exhibit extremely low pulse-to-pulse energy fluctuations nor a particularly clean beam profile. The experimental demonstration is numerically modeled, revealing the exact same mechanisms at work as at shorter input pulse duration. Additionally, the role of controlled beam clipping with an adjustable aperture is numerically substantiated
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