Attosecond Pulse Amplification in a Plasma-Based X-Ray Laser Dressed by an Infrared Laser Field

Abstract

We suggest a technique to amplify a train of attosecond pulses, produced by high-harmonic generation (HHG) of an infrared (IR) laser field, in an active medium of a plasma-based X-ray laser. This technique is based on modulation of transition frequency of the X-ray laser by the same IR field, as used to generate the harmonics, via linear Stark effect, which results in redistribution of the resonant gain and simultaneous amplification of a wide set of harmonics in the incident field. We propose an experimental implementation of the suggested technique in active medium of C 5+ ions at wavelength 3.4 nm in the "water window" range and show the possibility to amplify by two orders of magnitude a train of attosecond pulses with pulse duration down to 100 as. We show also a possibility to isolate a single attosecond pulse from the incident attosecond pulse train during its amplification in optically deep modulated medium. Abstract:In this supplemental material we derive an analytical solution describing an amplification of the highharmonic field in an active medium of a plasma-based X-ray laser in the linear regime within the three-level medium model and constant population inversion approximation. We provide also more detailed numerical study of an amplification process in both linear and nonlinear regimes taking into account a saturation effect within the fivelevel medium model.

Amplification of Elliptically Polarized Sub-Femtosecond Pulses in Neon-Like X-Ray Laser Modulated By An IR Field

“…Both possibilities are provided by coherent dressing of the neon-like active medium of an X-ray laser with an intense infrared (IR) laser field. It is closely related to our recent work [27], which has shown the possibility to amplify a set of linearly polarized HHs in a hydrogenlike active medium of a plasma-based X-ray laser dressed by a replica of a fundamental-frequency IR field with the same linear polarization. However, in the hydrogenlike medium the amplification of elliptically or circularly polarized HHs is prohibited, since the redistribution of the gain to the frequencies of harmonics is caused by the IR-field-induced sub-laser-cycle linear Stark effect and occurs only for XUV/X-rays with the same linear polarization as that of the modulating field, whereas for radiation with orthogonal polarization the gain remains localized at the single resonance frequency.…”

Temporal and spectral control of the X-ray pulses in a resonant medium with a modulated transition frequency

“…It is worth noting that the considered technique of the atomic transition frequency modulation is rather general. In particular, as shown in our recent works [17][18][19] , it can be used also for generation of the attosecond extreme ultraviolet and x-ray pulses or amplification of the attosecond pulses produced via HHG in the active medium of a plasma-based x-ray laser modulated by a strong infrared laser field.…”

Enhanced Amplification of Attosecond Pulses in a Hydrogen-like Plasma-Based X-ray Laser Modulated by an Infrared Field at the Second Harmonic of Fundamental Frequency

“…In recent work [19], we proposed a method for amplifying a train of attosecond pulses formed by a set of high-order harmonics of the infrared (IR) field in a hydrogen-like active Photonics 2022, 9, 51 2 of 21 medium of a plasma-based X-ray laser, which is simultaneously irradiated with a replica of the fundamental-frequency IR field used to generate the high harmonics. Due to the linear Stark effect, the positions of the excited-state energy levels of the resonant ions of the active medium follow the local value of the electric field of the laser wave in time and space.…”

“…In this case, if the harmonics of different orders at the entrance to the medium are comparable in amplitude, are in-phase, and form a sequence of attosecond pulses, then in the process of amplification, the spectral-temporal properties of radiation (such as the relative amplitudes and phases of harmonics and, as a consequence, the shape and duration of the pulses) are preserved. In [19], it was shown that it is possible to amplify attosecond pulses formed by a set of high harmonics in the "water window" range (2.3-4.4 nm) by one to two orders of magnitude in intensity in the active medium of hydrogen-like C 5+ ions.…”