Alexander Mitrofanov - Academia.edu (original) (raw)
Papers by Alexander Mitrofanov
2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)
Many atmospheric applications such as free-space communication or spectroscopy require targeted d... more Many atmospheric applications such as free-space communication or spectroscopy require targeted delivery of high-energy ultrashort pulses with a good beam quality. Often atmospheric turbulences complicate this task, causing random variations of the refractive index and resulting in fluctuations of light intensity on the target. Propagation of light in filamentation regime, when intensity is clamped, to a certain extent helps to overtake this problem, but brings ionization-related problems, such as energy loss, temporal pulse splitting, etc. Moreover, maximum peak power Ppeak, which can be delivered in a single filament is limited to about ten critical powers of self-focusing Pcrit, after which multiple filamentation and hence small-scale beam distortions take place. In the case of Ti:Sapphire drivers delivering 40-fs, 800-nm pulses, the energy in a single filament in air doesn't exceed 1 mJ, unless special conditions are applied [1]. However, since Pcrit∼λ2 (λ is the driver wavelength), essentially more energy can be deposited in a single filament driven by 3.9-μm pulses [2]. Furthermore, mid-IR spectral range is beneficial in virtue of lower ionization rates and higher resistance to modulation instabilities and scattering by natural atmospheric obstacles, such as water droplets [3]. Finally, a unique combination of high atmospheric transparency and anomalous dispersion of air between 3.6–4.2 μm promote an opportunity for a lossless high-energy ultrashort pulse delivery and simultaneous solitonic self-compression [4]. However, multiple molecular resonances responsible for the anomalous dispersion also complicate filamentation dynamics by adding a new channel of energy loss, namely nonlinear enhanced absorption losses [2,5], when mainly stimulated rotational Raman scattering (SRRS) governs spectral dynamics dominated by an essential spectral redshift and immediate absorption of newly generated spectral components by CO2, having vibrational resonance in the vicinity of 4.2 μm. Due to this non-linearly enhanced absorption up to 50% of energy can be lost over several meters of propagation of 30 mJ 130-fs pulses [2]. However, since the intrapulse SRRS is sensitive to a temporal spacing between spectral components, pre-chirping of drivers pulses can help to reduce and control the energy loss. Moreover, we have demonstrated, that a proper choice of the chirp can also lead to ∼5-fold self-compression in time and postponed onset of filamentation in space, what fulfils a goal of targeted high-energy ultrashort pulse delivery.
Journal of Raman Spectroscopy, Oct 29, 2021
Laser Congress 2017 (ASSL, LAC), 2017
2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), 2017
Variation of the sign of dispersion in air in the vicinity of 3.6 pm [1] makes propagation and fi... more Variation of the sign of dispersion in air in the vicinity of 3.6 pm [1] makes propagation and filamentation of mid-IR pulses extremely sensitive to the chirp, which allows to take control over the temporal pulse splitting, spectral broadening, energy losses and spatial profile. Here we report on filamentation of 30-mJ, 3.9-pm pulses produced by a hybrid OPA/OPCPA system [2]. Filamentation in ambient air is assisted by loose 7-m focusing and controlled by adjusting the chirp of the output of the OPCPA system.
This document provides supplementary information to "Ultraviolet-to-millimeter-band supercontinua... more This document provides supplementary information to "Ultraviolet-to-millimeter-band supercontinua driven by ultrashort mid-infrared laser pulses," https://doi.org/10.1364/OPTICA.7.000015, offering an expanded description of the methods and models used in our work to analyze and understand UV-to-mm-band supercontinua driven by ultrashort, high-peak-power mid-infrared laser pulses. Technical details of the analysis of phase-matching effects in multidecade supercontinuum generation by mid-infrared laser pulses are also provided.
Journal of Lightwave Technology, 2021
Ultrafast nonlinear dynamics driven by high-peak-power ultrashort mid-infrared (mid-IR) pulses gi... more Ultrafast nonlinear dynamics driven by high-peak-power ultrashort mid-infrared (mid-IR) pulses gives rise to ultrabroadband radiation whose spectrum spans over multiple decades, stretching from the terahertz (THz) to the microwave range. We show that, despite its enormous, multidecade bandwidth, an accurate spectral and spatial-mode characterization of this radiation is possible via a suitable combination of mutually complementary signal-analysis methods borrowed from ultrafast optics, radioelectronics, THz photonics, and microwave engineering. This analysis reveals intense subgigahertz radiation emitted as a part of mid-IR-driven supercontinuum generation and shows that microwave-to-THz field waveforms can almost reach the diffraction limit in their beam focusability, yielding field strengths above ≈3 MV/cm.
Optics Letters, 2021
Spectral analysis of high-order harmonics generated by ultrashort mid-infrared pulses in molecula... more Spectral analysis of high-order harmonics generated by ultrashort mid-infrared pulses in molecular nitrogen reveals well-resolved signatures of inverse Raman scattering, showing up near the frequencies of prominent vibrational transitions of nitrogen molecules. When tuned on a resonance with the v'=0→v''=0 pathway within the B3Πg→C3Πu second positive system of molecular nitrogen, the eleventh harmonic of a 3.9 µm, 80 fs driver is shown to acquire a distinctive antisymmetric spectral profile with red-shifted bright and blue-shifted dark features as indicators of stimulated Raman gain and loss. This high-harmonic setting extends the inverse Raman effect to a vast class of strong-field light-matter interaction scenarios.
EPJ Web of Conferences, 2019
We examine mid-IR light bullets generated in ambient air. 2-optical cycle pulses confined in spac... more We examine mid-IR light bullets generated in ambient air. 2-optical cycle pulses confined in space are generated in filamentation regime. Few-fold solitonic self-compression is achieved for strongly chirped mid-IR pulses.
Lasers Congress 2016 (ASSL, LSC, LAC), 2016
We present post-compression of 22-mJ 90-fs pulses at 3.9 µm via spectralbroadening in a noble-gas... more We present post-compression of 22-mJ 90-fs pulses at 3.9 µm via spectralbroadening in a noble-gas-filled 1 mm core diameter 3 meter long capillary with over 60% throughput and recompressed in a bulk BaF2 plate down to 33 fs.
Conference on Lasers and Electro-Optics, 2016
We report on self-compression of sub-100 fs, >20 mJ md-IR pulses in transparent dielectrics an... more We report on self-compression of sub-100 fs, >20 mJ md-IR pulses in transparent dielectrics and filaments ignited in ambient air. Combination of both permits generation of TW-level homogeneously compressed two-optical-cycle mid-IR pulses.
International Conference on Ultrafast Phenomena, 2016
We report self-action of 0.5-TW peak-power few-cycle 4-um pulses in air and bulk dielectrics that... more We report self-action of 0.5-TW peak-power few-cycle 4-um pulses in air and bulk dielectrics that is strikingly different compared to the case of near-IR drivers. An example of scalable nonlinear self-compression of 20-mJ is highlighted.
2009 Conference on Lasers & Electro Optics & The Pacific Rim Conference on Lasers and Electro-Optics, 2009
ABSTRACT
Springer Series in Chemical Physics, 2009
ABSTRACT
Nonlinear Optics and Applications III, 2009
ABSTRACT
Advances in Optical Materials, 2011
ABSTRACT Changes in the spectral width of Auger emission reveal transient depletion of excited st... more ABSTRACT Changes in the spectral width of Auger emission reveal transient depletion of excited states prepared using attosecond XUV pulses by strong phase-stable few-cycle pulses. Additionally, interference of photoelectrons and Auger electrons is observed.
International Conference on Ultrafast Phenomena, 2010
ABSTRACT
Advances in Optical Materials, 2011
ABSTRACT
Scientific reports, 2015
Filamentation of ultrashort laser pulses in the atmosphere offers unique opportunities for long-r... more 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 fil...
International Conference on Ultrafast Phenomena, 2010
The cascaded Auger decay following excitation with 92-eV soft-X-ray pulses from the 3p-subshell i... more The cascaded Auger decay following excitation with 92-eV soft-X-ray pulses from the 3p-subshell in Krypton has been energy-and-time-resolved for the first time. The decay time of the 4s-14p-1np→4p-2+e transition is measured to be 50±10 fs.
International Conference on Ultrafast Phenomena, 2010
ABSTRACT In the presence of an IR-field, high-energy Auger-electrons are emitted with the same ki... more ABSTRACT In the presence of an IR-field, high-energy Auger-electrons are emitted with the same kinetic energy as IR-streaked electrons directly XUV-ionized from the 4s-subshell in Krypton. Interference of the two electronic wave-packets is experimentally observed.
2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)
Many atmospheric applications such as free-space communication or spectroscopy require targeted d... more Many atmospheric applications such as free-space communication or spectroscopy require targeted delivery of high-energy ultrashort pulses with a good beam quality. Often atmospheric turbulences complicate this task, causing random variations of the refractive index and resulting in fluctuations of light intensity on the target. Propagation of light in filamentation regime, when intensity is clamped, to a certain extent helps to overtake this problem, but brings ionization-related problems, such as energy loss, temporal pulse splitting, etc. Moreover, maximum peak power Ppeak, which can be delivered in a single filament is limited to about ten critical powers of self-focusing Pcrit, after which multiple filamentation and hence small-scale beam distortions take place. In the case of Ti:Sapphire drivers delivering 40-fs, 800-nm pulses, the energy in a single filament in air doesn't exceed 1 mJ, unless special conditions are applied [1]. However, since Pcrit∼λ2 (λ is the driver wavelength), essentially more energy can be deposited in a single filament driven by 3.9-μm pulses [2]. Furthermore, mid-IR spectral range is beneficial in virtue of lower ionization rates and higher resistance to modulation instabilities and scattering by natural atmospheric obstacles, such as water droplets [3]. Finally, a unique combination of high atmospheric transparency and anomalous dispersion of air between 3.6–4.2 μm promote an opportunity for a lossless high-energy ultrashort pulse delivery and simultaneous solitonic self-compression [4]. However, multiple molecular resonances responsible for the anomalous dispersion also complicate filamentation dynamics by adding a new channel of energy loss, namely nonlinear enhanced absorption losses [2,5], when mainly stimulated rotational Raman scattering (SRRS) governs spectral dynamics dominated by an essential spectral redshift and immediate absorption of newly generated spectral components by CO2, having vibrational resonance in the vicinity of 4.2 μm. Due to this non-linearly enhanced absorption up to 50% of energy can be lost over several meters of propagation of 30 mJ 130-fs pulses [2]. However, since the intrapulse SRRS is sensitive to a temporal spacing between spectral components, pre-chirping of drivers pulses can help to reduce and control the energy loss. Moreover, we have demonstrated, that a proper choice of the chirp can also lead to ∼5-fold self-compression in time and postponed onset of filamentation in space, what fulfils a goal of targeted high-energy ultrashort pulse delivery.
Journal of Raman Spectroscopy, Oct 29, 2021
Laser Congress 2017 (ASSL, LAC), 2017
2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), 2017
Variation of the sign of dispersion in air in the vicinity of 3.6 pm [1] makes propagation and fi... more Variation of the sign of dispersion in air in the vicinity of 3.6 pm [1] makes propagation and filamentation of mid-IR pulses extremely sensitive to the chirp, which allows to take control over the temporal pulse splitting, spectral broadening, energy losses and spatial profile. Here we report on filamentation of 30-mJ, 3.9-pm pulses produced by a hybrid OPA/OPCPA system [2]. Filamentation in ambient air is assisted by loose 7-m focusing and controlled by adjusting the chirp of the output of the OPCPA system.
This document provides supplementary information to "Ultraviolet-to-millimeter-band supercontinua... more This document provides supplementary information to "Ultraviolet-to-millimeter-band supercontinua driven by ultrashort mid-infrared laser pulses," https://doi.org/10.1364/OPTICA.7.000015, offering an expanded description of the methods and models used in our work to analyze and understand UV-to-mm-band supercontinua driven by ultrashort, high-peak-power mid-infrared laser pulses. Technical details of the analysis of phase-matching effects in multidecade supercontinuum generation by mid-infrared laser pulses are also provided.
Journal of Lightwave Technology, 2021
Ultrafast nonlinear dynamics driven by high-peak-power ultrashort mid-infrared (mid-IR) pulses gi... more Ultrafast nonlinear dynamics driven by high-peak-power ultrashort mid-infrared (mid-IR) pulses gives rise to ultrabroadband radiation whose spectrum spans over multiple decades, stretching from the terahertz (THz) to the microwave range. We show that, despite its enormous, multidecade bandwidth, an accurate spectral and spatial-mode characterization of this radiation is possible via a suitable combination of mutually complementary signal-analysis methods borrowed from ultrafast optics, radioelectronics, THz photonics, and microwave engineering. This analysis reveals intense subgigahertz radiation emitted as a part of mid-IR-driven supercontinuum generation and shows that microwave-to-THz field waveforms can almost reach the diffraction limit in their beam focusability, yielding field strengths above ≈3 MV/cm.
Optics Letters, 2021
Spectral analysis of high-order harmonics generated by ultrashort mid-infrared pulses in molecula... more Spectral analysis of high-order harmonics generated by ultrashort mid-infrared pulses in molecular nitrogen reveals well-resolved signatures of inverse Raman scattering, showing up near the frequencies of prominent vibrational transitions of nitrogen molecules. When tuned on a resonance with the v'=0→v''=0 pathway within the B3Πg→C3Πu second positive system of molecular nitrogen, the eleventh harmonic of a 3.9 µm, 80 fs driver is shown to acquire a distinctive antisymmetric spectral profile with red-shifted bright and blue-shifted dark features as indicators of stimulated Raman gain and loss. This high-harmonic setting extends the inverse Raman effect to a vast class of strong-field light-matter interaction scenarios.
EPJ Web of Conferences, 2019
We examine mid-IR light bullets generated in ambient air. 2-optical cycle pulses confined in spac... more We examine mid-IR light bullets generated in ambient air. 2-optical cycle pulses confined in space are generated in filamentation regime. Few-fold solitonic self-compression is achieved for strongly chirped mid-IR pulses.
Lasers Congress 2016 (ASSL, LSC, LAC), 2016
We present post-compression of 22-mJ 90-fs pulses at 3.9 µm via spectralbroadening in a noble-gas... more We present post-compression of 22-mJ 90-fs pulses at 3.9 µm via spectralbroadening in a noble-gas-filled 1 mm core diameter 3 meter long capillary with over 60% throughput and recompressed in a bulk BaF2 plate down to 33 fs.
Conference on Lasers and Electro-Optics, 2016
We report on self-compression of sub-100 fs, >20 mJ md-IR pulses in transparent dielectrics an... more We report on self-compression of sub-100 fs, >20 mJ md-IR pulses in transparent dielectrics and filaments ignited in ambient air. Combination of both permits generation of TW-level homogeneously compressed two-optical-cycle mid-IR pulses.
International Conference on Ultrafast Phenomena, 2016
We report self-action of 0.5-TW peak-power few-cycle 4-um pulses in air and bulk dielectrics that... more We report self-action of 0.5-TW peak-power few-cycle 4-um pulses in air and bulk dielectrics that is strikingly different compared to the case of near-IR drivers. An example of scalable nonlinear self-compression of 20-mJ is highlighted.
2009 Conference on Lasers & Electro Optics & The Pacific Rim Conference on Lasers and Electro-Optics, 2009
ABSTRACT
Springer Series in Chemical Physics, 2009
ABSTRACT
Nonlinear Optics and Applications III, 2009
ABSTRACT
Advances in Optical Materials, 2011
ABSTRACT Changes in the spectral width of Auger emission reveal transient depletion of excited st... more ABSTRACT Changes in the spectral width of Auger emission reveal transient depletion of excited states prepared using attosecond XUV pulses by strong phase-stable few-cycle pulses. Additionally, interference of photoelectrons and Auger electrons is observed.
International Conference on Ultrafast Phenomena, 2010
ABSTRACT
Advances in Optical Materials, 2011
ABSTRACT
Scientific reports, 2015
Filamentation of ultrashort laser pulses in the atmosphere offers unique opportunities for long-r... more 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 fil...
International Conference on Ultrafast Phenomena, 2010
The cascaded Auger decay following excitation with 92-eV soft-X-ray pulses from the 3p-subshell i... more The cascaded Auger decay following excitation with 92-eV soft-X-ray pulses from the 3p-subshell in Krypton has been energy-and-time-resolved for the first time. The decay time of the 4s-14p-1np→4p-2+e transition is measured to be 50±10 fs.
International Conference on Ultrafast Phenomena, 2010
ABSTRACT In the presence of an IR-field, high-energy Auger-electrons are emitted with the same ki... more ABSTRACT In the presence of an IR-field, high-energy Auger-electrons are emitted with the same kinetic energy as IR-streaked electrons directly XUV-ionized from the 4s-subshell in Krypton. Interference of the two electronic wave-packets is experimentally observed.