Over the past decade intense laser fields with a single-cycle duration and even shorter, subcycle multicolour field transients have been generated and applied to drive attosecond phenomena in ...strong-field physics. Because of their extensive bandwidth, single-cycle fields cannot be emitted or amplified by laser sources directly and, as a rule, are produced by external pulse compression-a combination of nonlinear optical spectral broadening followed up by dispersion compensation. Here we demonstrate a simple robust driver for high-field applications based on this Kagome fibre approach that ensures pulse self-compression down to the ultimate single-cycle limit and provides phase-controlled pulses with up to a 100 μJ energy level, depending on the filling gas, pressure and the waveguide length.
An observation of neutron-antineutron oscillations (n-nover ¯), which violate both B and B-L conservation, would constitute a scientific discovery of fundamental importance to physics and cosmology. ...A stringent upper bound on its transition rate would make an important contribution to our understanding of the baryon asymmetry of the Universe by eliminating the postsphaleron baryogenesis scenario in the light quark sector. We show that one can design an experiment using slow neutrons that in principle can reach the required sensitivity of τ_{n-nover ¯}∼10^{10} s in the oscillation time, an improvement of ∼10^{4} in the oscillation probability relative to the existing limit for free neutrons. The improved statistical accuracy needed to reach this sensitivity can be achieved by allowing both the neutron and antineutron components of the developing superposition state to coherently reflect from mirrors. We present a quantitative analysis of this scenario and show that, for sufficiently small transverse momenta of n/nover ¯ and for certain choices of nuclei for the n/nover ¯ guide material, the relative phase shift of the n and nover ¯ components upon reflection and the nover ¯ annihilation rate can be small enough to maintain sufficient coherence to benefit from the greater phase space acceptance the mirror provides.
The physics of strong-field applications requires driver laser pulses that are both energetic and extremely short. Whereas optical amplifiers, laser and parametric, boost the energy, their gain ...bandwidth restricts the attainable pulse duration, requiring additional nonlinear spectral broadening to enable few or even single cycle compression and a corresponding peak power increase. Here we demonstrate, in the mid-infrared wavelength range that is important for scaling the ponderomotive energy in strong-field interactions, a simple energy-efficient and scalable soliton-like pulse compression in a mm-long yttrium aluminium garnet crystal with no additional dispersion management. Sub-three-cycle pulses with >0.44 TW peak power are compressed and extracted before the onset of modulation instability and multiple filamentation as a result of a favourable interplay between strong anomalous dispersion and optical nonlinearity around the wavelength of 3.9 μm. As a manifestation of the increased peak power, we show the evidence of mid-infrared pulse filamentation in atmospheric air.
Filamentation of ultrashort laser pulses in the atmosphere offers unique opportunities for long-range transmission of high-power laser radiation and standoff detection. With the critical power of ...self-focusing scaling as the laser wavelength squared, the quest for longer-wavelength drivers, which would radically increase the peak power and, hence, the laser energy in a single filament, has been ongoing over two decades, during which time the available laser sources limited filamentation experiments in the atmosphere to the near-infrared and visible ranges. Here, we demonstrate filamentation of ultrashort mid-infrared pulses in the atmosphere for the first time. We show that, with the spectrum of a femtosecond laser driver centered at 3.9 μm, right at the edge of the atmospheric transmission window, radiation energies above 20 mJ and peak powers in excess of 200 GW can be transmitted through the atmosphere in a single filament. Our studies reveal unique properties of mid-infrared filaments, where the generation of powerful mid-infrared supercontinuum is accompanied by unusual scenarios of optical harmonic generation, giving rise to remarkably broad radiation spectra, stretching from the visible to the mid-infrared.
When coupled to characteristic, fingerprint vibrational and rotational motions of molecules, an electromagnetic field with an appropriate frequency and waveform offers a highly sensitive, highly ...informative probe, enabling chemically specific studies on a broad class of systems in physics, chemistry, biology, geosciences, and medicine. The frequencies of these signature molecular modes, however, lie in a region where accurate spectroscopic measurements are extremely difficult because of the lack of efficient detectors and spectrometers. Here, we show that, with a combination of advanced ultrafast technologies and nonlinear-optical waveform characterization, time-domain techniques can be advantageously extended to the metrology of fundamental molecular motions in the mid-infrared. In our scheme, the spectral modulation of ultrashort mid-infrared pulses, induced by rovibrational motions of molecules, gives rise to interfering coherent dark waveforms in the time domain. These high-visibility interference patterns can be read out by cross-correlation frequency-resolved gating of the field in the visible generated through ultrabroadband four-wave mixing in a gas phase.
A representative class of matrix functions from the Wiener algebra of order 2 admitting an effective factorization is found. The factorization problem for elements of this class is reduced to a ...truncated Wiener–Hopf equation with a contracting integral operator. The latter guarantees, as will be shown in the article, the existence of a canonical factorization and its explicit construction for matrix functions from the class under consideration.
Nowadays, the technical advances call for efficient electromagnetic interference (EMI) shielding of transparent devices which may be subject to data theft. We developed Cu–Ag and Ni–Ag meshes on ...flexible PET substrate for highly efficiency transparent EMI shielding coating. Cu–Ag and Ni–Ag meshes obtained with galvanic deposition of copper and nickel on thin Ag seed mesh which was made by cracked template method. Coefficients
S
11
,
S
21
and shielding efficiency (
SE
) were measured for Cu–Ag and Ni–Ag meshes in X-band (8–12 GHz) and K-band (18–26.5 GHz). 90 s copper deposition increase
SE
from 23.2 to 43.7 dB at 8 GHz with a transparency of 82.2% and a sheet resistance of 0.25 Ω/sq. The achieved maximum
SE
was 47.6 dB for Cu–Ag mesh with 67.8% transparency and 41.1 dB for Ni–Ag mesh with 77.8% transparency. Cu–Ag and Ni–Ag meshes have high bending and long-term stability. Minimum bend radius is lower than 100 µm. This effect allows to produce different forms of transparent shielding objects, for example, origami method. Our coatings are the leading among all literary solutions in three-dimensional coordinates: of sheet resistance–optical transmittance–cost of produced.
Graphical abstract
A method for reducing the factorization problem for an arbitrary matrix function with nonnegative total index in (an everywhere dense subalgebra of) the Wiener algebra of order 2 to the truncated ...Wiener–Hopf equation is found. With the help of the method, an efficient factorization of one class of matrix functions in the Wiener algebra of order 2 is constructed.
PDF
