arXiv subjects

Jingqin Su

Publications and source records attributed to Jingqin Su.

5 recordsLinked to original sources

arXiv2025

Express Diagnostic of Intense Laser-driven MeV Radiation Source using Copper Isotopes

We explored the generation and diagnosis of high-brightness MeV bremsstrahlung radiation caused by intense beam of relativistic electrons propagating in a tantalum converter. The intense electron beam was produced through direct laser acceleration mechanism in the interaction of relativistic high-power sub-ps laser pulse with near critical density plasma. We propose to detect the divergence angle and photon fluence of high-brightness and high-energy gamma radiation source based on the nuclear activation method. The radioactive 62^Cu was generated through photonuclear reactions 63^Cu(gamma,n) 62^Cu and the subsequent beta^+ decay of 62^Cu was measured to derive characteristics of the gamma radiation source. This method provides an express approach to diagnose the laser-driven MeV radiation source and a potential efficient way to produce 62^Cu isotopes.

physics.acc-ph↗

arXiv2023

Generation of subcycle isolated attosecond pulses by pumping ionizing gating

We present a novel approach named as pumping ionizing gating (PIG) for the generation of isolated attosecond pulses (IAPs). In this regime, a short laser is used to ionize a pre-existing gas grating, creating a fast-extending plasma grating(FEPG) having an ionization front propagating with the velocity of light. A low-intensity long counterpropagating pump pulse is then reflected by a very narrow region of the ionization front, only where the Bragg conditions for resonant reflection is satisfied. Consequently, the pump reflection is confined within a sub-cycle region called PIG, and forms a wide-band coherent IAP in combination with the frequency up-conversion effect due to the plasma gradient. This approach results in a new scheme to generate IAPs fromlong picosecond pump pulses. Three-dimensional (3D) simulations show that a 1.6-ps, 1-μm pump pulse can be used to generate a 330 as laser pulse with a peak intensity approximately 33 times that of the pump and a conversion efficiency of around 0.1%.These results highlight the potential of the PIG method for generating IAPs with high conversion efficiency and peak intensity.

physics.optics↗

arXiv2021

Laser Compression via fast-extending plasma gratings

It is proposed a new method of compressing laser pulse by fast extending plasma gratings(FEPG), which is created by ionizing the hypersound wave generated by stimulated Brillouin scattering(SBS) in the background gas. Ionized by a short laser pulse, the phonon forms a light-velocity FEPG to fully reflect a resonant pump laser. As the reflecting surface moves with a light velocity, the reflected pulse is temporally overlapped and compressed. This regime is supported by the simulation results of a fully kinetic particle-in-cell(PIC) code Opic with a laser wavelength of 1um, displaying a pump pulse is compressed from 13ps to a few cycles(7.2fs), with an efficiency close to 80%. It is a promising method to produce critical laser powers due to several features: high efficiency without a linear stage, robustness to plasma instabilities, no seed and a wide range of pump intensity.

physics.plasm-ph↗

arXiv2021

Self-compression of stimulated Raman backscattering by flying focus

A novel regime of self-compression is proposed for plasma-based backward Raman amplification(BRA) upon flying focus. By using a pumping focus moving with a speed equal to the group velocity of stimulated Raman backscattering(SRBS), only a short part of SRBS which does always synchronize with the flying focus can be amplified. Due to the asymmetrical amplification, the pulse can be directly compressed in the linear stage of BRA. Therefore, instead of a short pulse, the Raman spontaneous or a long pulse can seed the BRA amplifiers. The regime is supported by the 2D particle-in-cell(PIC) simulation without a seed, presenting that the pump pulse is compressed from 26ps to 116fs, with an output amplitude comparable with the case of a well-synchronized short seed. This method provides a significant way to simplify the Raman amplifiers and overcome the issue of synchronization jitter between the pump and the seed.

physics.plasm-ph↗

arXiv2018

Passively Q-switching cylindrical vector beam fiber laser operating in high-order mode

We experimentally demonstrate a linear-cavity all-fiber passively Q-switching cylindrical vector beam (CVB) laser operating in high-order mode. This CVB fiber laser operates without any mode converter which always leads to high insertion loss, and it can realize high efficiency. In this fiber laser, the stable Q-switching pulse is achieved with a slope efficiency of 39%. By properly adjusting the polarization controllers, radially polarized and azimuthally polarized beams can be obtained. Our work proves the feasibility of achieving the stable Q-switching CVB pulse with high-order mode directly oscillating, and it may have an enormous potential for enhancing the efficiency.

physics.optics↗