Nikolay A. Panov

Nikolay A. Panov

Lomonosov Moscow State University
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Nikolay A. Panov has a total of 118 co-authors. Here are the top co-authors by number of shared publications:

Latest Publications

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    Highly efficient microwave emission from DC-biased femtosecond laser filament in air

    by A. A. Ushakov, N. R. Vrublevskaya, E. V. Mitina, D. S. Uryupina, P. A. Chizhov, T. V. Dolmatov, V. V. Bulgakova, K. A. Galuyk, S. V. Garnov, N. A. Panov, et al.

    We report observation of microwave radiation from the femtosecond filament in air biased by 10-kV/cm static transverse field with an amplitude ∼ 2 orders of magnitude higher than in the unbiased or weakly biased cases. Such powerful microwaves with the broadband spectrum at least from 2 to 13 GHz propagate at relatively small angles with respect to the laser beam axis. We propose and justify the physical mechanism of microwave emission: the microwaves are generated by the external-field-induced transverse plasma current which decreases during 100–500 ps after the laser pulse due to the electron-ion recombination.

    Cited by 1
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    Second-harmonic generation in the air-based femtosecond plasma under loose focusing

    by I. A. Nikolaeva, D. E. Shipilo, G. E. Rizaev, A. V. Koribut, T. A. Dick, D. V. Pushkarev, M. V. Levus, Ya. V. Grudtsyn, N. R. Vrublevskaya, N. A. Panov, et al.

    We used filamentation of 940 nm, 90 fs, up to 6.5 mJ pulse to measure the spatial and spectral distributions of the second harmonic with 10^{-9} conversion efficiency in comparatively long focusing geometry (40 cm and 100 cm focal lengths, ≥1 cm filament), as well as spectral distributions of the second harmonic with about an order of magnitude higher conversion efficiency in tight focusing geometry (8 cm focal length, ∼1mm filament). Through integration of the vectorial second-order current over the (t,r,z)-simulated plasma channel, we identified the second-harmonic generation region, outside of which the ω-2ω phase mismatch quenches the second-harmonic energy increment. The unified description of the even harmonic emission based on the vectorial second-order current shows that the two lobes of the terahertz beam broken along the laser polarization are oriented perpendicularly to the two lobes of the second harmonic beam, in agreement with the experiment.

    Cited by 2
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    Long-wavelength spectral shift in an ultraviolet filament

    by D. E. Shipilo, N. R. Vrublevskaya, I. A. Nikolaeva, L. V. Seleznev, D. V. Pushkarev, G. E. Rizaev, M. V. Levus, A. A. Ionin, N. A. Panov, O. G. Kosareva

    Cited by 1
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    Time-domain model for signal transformation in semiconductor optical amplifiers for bit error rate estimation in communication lines

    by Paul Ya. Ilyushin, Daniil E. Shipilo, Irina A. Nikolaeva, Nikolay A. Panov, Olga G. Kosareva

    Subject of study. The study focuses on a fiber-optic communication line incorporating semiconductor optical amplifiers, specifically spontaneous emission and the nonlinear effects in the amplifiers that lead to digital signal transmission errors. Aim of study. The aim of this study was to develop a model of a fiber-optic communication line with integrated semiconductor optical amplifiers, taking into account distortion sources for both weak and strong signals, namely, spontaneous emission and nonlinear effects in the active medium of the amplifiers. Method. The study was conducted using numerical simulations. The model accounted for the propagation of radiation along a 100-km optical fiber span, during which extensive dispersive spreading and absorption occur. The average power of the laser radiation after this span determined the amplifier’s quasi-stationary operating mode, including the power of spontaneous radiation in it. In this operating mode, the transformation of a quadrature-modulated signal within the semiconductor amplifier was calculated. Main results. A numerical model of a fiber-optic communication line with integrated semiconductor optical amplifiers has been developed. This model has been used to analyze information loss in a quadrature-modulated signal; this information loss is attributed to gain dispersion, gain saturation, and spontaneous emission in the active medium of the amplifiers. When the laser pulse duration is 12 ps or longer, the amplifier’s input power dynamic range exceeds 20 dBm (from −37.5dBm to −17.5dBm). Within this range, compensation for amplifier-induced distortion is not required. Practical significance. The results obtained in this study can be used to increase data transmission rates in fiber-optic communication lines over distances ranging from hundreds to thousands of kilometers.

    Cited by 1
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    Terahertz ring beam independent on ω –2ω phase offset in the course of two-color femtosecond filamentation

    by I. A. Nikolaeva, N. R. Vrublevskaya, G. E. Rizaev, D. V. Pushkarev, D. V. Mokrousova, D. E. Shipilo, N. A. Panov, L. V. Seleznev, A. A. Ionin, O. G. Kosareva, et al.

    We measured and simulated the spectrally resolved angular distributions of 0.3–1-THz emission from the two-color filament with its plasma length (∼40 mm) exceeding the dephasing length (∼25 mm) between the fundamental (740 nm) and the second harmonic (370 nm) pulses in air. We show that only the forwardly propagating on-axis terahertz (THz) radiation is sensitive to the variation of the phase offset φ between fundamental and second harmonics, while the ring-like THz beam carrying ≳80% of the overall THz yield is independent of φ. Utilization of the THz ring allows one to omit the tedious adjustment of the frequency-doubling crystal position in the experiment.

    Cited by 7
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    Scaling Law of THz Yield from Two-Color Femtosecond Filament for Fixed Pump Power

    by Irina A. Nikolaeva, Daniil E. Shipilo, Nikolay A. Panov, Weiwei Liu, Andrei B. Savel’ev, Olga G. Kosareva

    In 3D + time numerical simulations, we study the wavelength scaling law for the energy of terahertz (THz) radiation emitted from a two-color femtosecond filament, which forms during cofocusing into air the fundamental and second harmonics of the laser pulse. In our simulations, the central wavelength of the fundamental harmonic varied from 0.8 to 8 μm and the numerical aperture varied from 0.006 to 0.03. While the harmonics and supercontinuum development are not extreme, so the harmonics spectra are clearly separated, the energy of the generated THz radiation is proportional to the oscillation energy of the electrons, which grows as the squared pump wavelength, and the total number of free electrons in the filament, which decreases quasi-exponentially with the pump wavelength. As a result, the scaling law for the THz energy on the pump wavelength is nonmonotonic with the maximum at 1.6–4 μm depending on the focusing conditions.

    Cited by 13
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    Nonlinear Propagation and Filamentation on 100 Meter Air Path of Femtosecond Beam Partitioned by Wire Mesh

    by Yuri E. Geints, Olga V. Minina, Ilia Yu. Geints, Leonid V. Seleznev, Dmitrii V. Pushkarev, Daria V. Mokrousova, Georgy E. Rizaev, Daniil E. Shipilo, Irina A. Nikolaeva, Maria V. Kurilova, et al.

    High-intensity (∼1 TW/cm2 and higher) region formed in the propagation of ∼60 GW, 90 fs Ti:Sapphire laser pulse on a ∼100 m path in air spans for several tens of meters and includes a plasma filament and a postfilament light channel. The intensity in this extended region is high enough to generate an infrared supercontinuum wing and to initiate laser-induced discharge in the gap between the electrodes. In the experiment and simulations, we delay the high-intensity region along the propagation direction by inserting metal-wire meshes with square cells at the laser system output. We identify the presence of a high-intensity region from the clean-spatial-mode distributions, appearance of the infrared supercontinuum wing, and occurrence of the laser-induced discharge. In the case of free propagation (without any meshes), the onset of the high-intensity zone is at 40–52 m from the laser system output with ∼30 m extension. Insertion of the mesh with 3 mm cells delays the beginning of the high-intensity region to 49–68 m with the same ∼30 m extension. A decrease in the cell size to 1 mm leads to both delay and shrinking of the high-intensity zone to 71–73 m and 6 m, respectively. Three-dimensional simulations in space confirm the mesh-induced delay of the high-intensity zone as the cell size decreases.

    Cited by 16
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    Low-Frequency Content of THz Emission from Two-Color Femtosecond Filament

    by Daniil E. Shipilo, Nikolay A. Panov, Irina A. Nikolaeva, Alexander A. Ushakov, Pavel A. Chizhov, Kseniia A. Mamaeva, Vladimir V. Bukin, Sergey V. Garnov, Olga G. Kosareva

    We experimentally investigate the low-frequency (below 1 THz) spectral content of broadband terahertz (THz) emission from two-color femtosecond filament formed by the 2.7-mJ, 40-fs, 800+400-nm pulse focused into air. For incoherent detection, we screened the Golay cell by the bandpass filters and measured the THz angular distributions at the selected frequencies ν=0.5, 1, 2 and 3 THz. The measured distributions of THz fluence were integrated over the forward hemisphere taking into account the transmittance of the filters, thus providing the estimation of spectral power at the frequencies studied. The spectral power decreases monotonically with the frequency increasing from 0.5 to 3 THz, thus showing that the maximum of THz spectrum is attained at ν≤0.5 THz. The THz waveform measured by electro-optical sampling (EOS) based on ZnTe crystal and transformed into the spectral domain shows that there exists the local maximum of the THz spectral power at ν≈1 THz. This disagrees with monotonic decrease of THz spectral power obtained from the filter-based measurements. We have introduced the correction to the spectral power reconstructed from EOS measurements. This correction takes into account different focal spot size for different THz frequencies contained in the broadband electromagnetic pulse. The corrected EOS spectral power is in semi-quantitative agreement with the one measured by a set of filters.

    Cited by 11
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    Superposition of 2ω and Electrostatic Field Induced Terahertz Waveforms in DC-Biased Two-Color Filament

    by Aleksandr Ushakov, Pavel Chizhov, Irina Nikolaeva, Daniil Shipilo, Nikolay Panov, Vladimir Bukin, Kseniia Mamaeva, Olga Kosareva, Sergey Garnov

    Increase in conversion efficiency from a femtosecond optical pump into broadband terahertz (THz) radiation is currently an essential issue since it boosts THz source performance for medicine and security applications. An air-plasma based THz radiation from a two-color femtosecond filament is the most efficient gas-based THz emitter, with a dipole local source having a maximum on the beam propagation axis. In this work, we show the novel advancement to THz yield increase with preservation of the forwardly directed dipole radiation. The two-color THz source can be enhanced if the filament plasma channel is placed into an external electrostatic field (DC bias), which is parallel to the second harmonic polarization direction. In the experiment, we produce a plasma channel from 800-nm, ∼50-fs, 2-mJ pulse with 200 μJ of 400-nm, ∼50-fs mixed with the pump, and allocate it between the electrodes carrying 7-kV/cm static field. Time-domain measurements and 3D+time simulations of THz waveforms from the two-color DC-biased filament show that the THz emission is the superposition of the THz waveforms generated in the 800+400-nm filament without a DC-bias and in the 800-nm (without 400-nm) plasma channel biased by 7-kV/cm static field. The additivity of the two local dipole THz sources is possible if the majority of free electrons are produced by the pump pulse.

    Cited by 5
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    Tracing Evolution of Angle-Wavelength Spectrum along the 40-m Postfilament in Corridor Air

    by Daria V. Mokrousova, Dmitrii V. Pushkarev, Nikolay A. Panov, Irina A. Nikolaeva, Daniil E. Shipilo, Nikita A. Zhidovtsev, Georgy E. Rizaev, Daria S. Uryupina, Arnaud Couairon, Aurélien Houard, et al.

    Postfilamentation channel resulting from filamentation of freely propagating 744-nm, 5-mJ, 110-fs pulse in the corridor air is examined experimentally and in simulations. The longitudinal extension of postfilament was determined to be 55–95 m from the compressor output. Using single-shot angle-wavelength spectra measurements, we observed a series of red-shifted maxima in the spectrum, localized on the beam axis with the divergence below 0.5 mrad. In the range 55–70 m, the number of maxima and their red-shift increase with the distance reaching 1 μm, while the pulse duration measured by the autocorrelation technique is approximately constant. Further on, for distances larger than 70 m and up to 95 m, the propagation is characterized by the suppressed beam divergence and unchanged pulse spectrum. The pulse duration increases due to the normal air dispersion.

    Cited by 7
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