Author: "Panagiotopoulos, Paris" - Searchworks@Jio Institute Digital Library Search Results

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Author: Panagiotopoulos, Paris, Whalen, Patrick, Kolesik, Miroslav, and Moloney, Jerome V.
Subjects: *FEMTOSECOND lasers, *OPTICAL information processing, *LASER communication systems, *SUBMILLIMETER waves, *RADIO frequency
Abstract: Mid-infrared ultrashort high energy laser sources are opening up new opportunities in science, including keV-class high harmonic generation and monoenergetic MeV-class proton acceleration. As new higher energy sources become available, potential applications for atmospheric propagation can dramatically grow to include stand-off detection, laser communications, shock-driven remote terahertz enhancement and extended long-lived thermal waveguides to transport high power microwave and radiofrequency waves. We reveal a new paradigm for long-range, low-loss, ultrahigh power ultrashort pulse propagation at mid-infrared wavelengths in the atmosphere. Before the onset of critical self-focusing, energy in the fundamental wave continually leaks into shock-driven spectrally broadened higher harmonics. A persistent near-invariant solitonic leading edge on the multi-terawatt pulse waveform transports most of the power over hundred-metre-long distances. Such light bullets are resistant to uncontrolled multiple filamentation and are expected to spark extensive research in optics, where the use of mid-infrared lasers is currently much under-utilized. [ABSTRACT FROM AUTHOR]
Published: 2015
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Author: Whalen, Patrick, Panagiotopoulos, Paris, Kolesik, Miroslav, and Moloney, Jerome V.
Subjects: *WAVELENGTHS, *ULTRASHORT laser pulses, *NONLINEAR systems, *LIGHT propagation, *KADOMTSEV-Petviashvili equation, *OPTICAL self-focusing
Abstract: We predict a paradigm shift in the nonlinear physics associated with ultrashort long-wavelength pulse propagation in gaseous and condensed media. Optical carrier shock formation, which profoundly modifies the underlying optical wave form, emerges prior to the onset of the well-known self-focusing collapse singularity. The canonical description of pulse propagation in this regime, where all nonlinear envelope descriptions fail, is identified as the full field carrier resolved modified Kadomtsev-Petviashili (MKP) equation. [ABSTRACT FROM AUTHOR]
Published: 2014
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Author: Panagiotopoulos, Paris, Kolesik, Miroslav, and Moloney, Jerome V.
Subjects: *NUMERICAL analysis, *SIMULATION methods & models, *ELECTRONIC modulation
Abstract: We numerically investigate the scaling behavior of midinfrared filaments at extremely high input energies. It is shown that, given sufficient power, kilometer-scale, low-loss atmospheric filamentation is attainable by prechirping the pulse. Fully resolved four-dimensional (xyzt) simulations show that, while in a spatially imperfect beam the modulation instability can lead to multiple hot-spot formation, the individual filaments are still stabilized by the recently proposed mechanism that relies on the temporal walk-off of short-wavelength radiation. [ABSTRACT FROM AUTHOR]
Published: 2016
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Author: Panagiotopoulos, Paris, Couairon, Arnaud, Kolesik, Miroslav, Papazoglou, Dimitris G., Moloney, Jerome V., and Tzortzakis, Stelios
Subjects: *COMPUTER simulation, *WAVE packets, *GAUSSIAN beams
Abstract: We numerically demonstrate that femtosecond ring-Airy wave packets are able to overcome the reference intensity clamping of 4?1013 W/cm² for filaments generated with Gaussian beams at low numerical apertures and form an intense sharp intensity peak on axis. Numerical simulations, with unidirectional propagation models for the pulse envelope and the carrier resolved electric field, reveal that the driving mechanism for this unexpected intensity increase is due to the self-generated plasma. The plasma formation, in conjunction with the circular geometry of the beam, force the wave packet into a multistage collapse process which takes place faster than the saturating mechanisms can compensate. We report here a nonstandard mechanism that increases the intensity of a collapsing wave packet, due to the joint contributions of the cubic phase of the Airy beam and the formation of a partially reflecting plasma. [ABSTRACT FROM AUTHOR]
Published: 2016
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Author: Suntsov, Sergiy, Abdollahpour, Daryoush, Papazoglou, Dimitrios G., Panagiotopoulos, Paris, Couairon, Arnaud, and Tzortzakis, Stelios
Subjects: *FEMTOSECOND lasers, *FILAMENTATION instability, *BESSEL beams, *RAYLEIGH scattering, *DISPERSION (Chemistry), *FEMTOSECOND pulses
Abstract: We demonstrate experimentally that by using transient plasma photonic lattices, the attributes of intense femtosecond laser filaments, such as peak intensity and length, can be dynamically controlled. The extended plasma lattice structure is generated using two co-propagating non-diffracting intense Bessel beams in water. The use of such transient lattice structures to control the competition between linear and nonlinear effects involved in filamentation opens the way for extensive control of the filamentation process. [ABSTRACT FROM AUTHOR]
Published: 2013
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