Enhanced XUV harmonics generation from diatomic gases using two orthogonally polarized laser fields

Abstract

Enhanced high repetition rate coherent extreme ultraviolet (XUV) harmonics represent efficient probe of electron dynamics in atoms, molecules and solids. In this work, we used orthogonally-polarized two-color laser field to generate strong even and odd high order harmonics from molecular gas targets. The dynamics of odd and even harmonics from O2, and N2 gases were investigated by employing single- and two-color laser fields using the fundamental radiation and second harmonic of 1030 nm, 37 fs, 50 kHz pulses. The relative efficiencies of harmonics were analyzed as a function of the thickness of the barium borate crystal used for second harmonic generation. Defocusing-assisted phase matching conditions were achieved in N2 gas for different groups of XUV harmonics.

Controlling LIPSS formation on Ni surface using near-infrared laser beam and its low-order harmonics

“…It can be seen from the AFM image that circular homogenous conical spikes were formed with pointy tops and average cones depth ∼485 nm and average surface roughness of 63 nm. The ablation depth from the impact of the laser pulses is mainly dependant on the absorbed laser fluence, which can be controlled by controlling the average power of the driving laser beam and the pulse duration [49,53]. Circular spikes structures were reported earlier in the literature and their formation mechanism were explained in terms of Marangoni shear-generated convection that leads to hydrothermal waves and eventually to microgrooves and microspikes formation [54,55].…”

High Harmonic Generation from Laser-Induced Plasmas of Ni-Doped CsPbBr3 Nanocrystals: Implications for Extreme Ultraviolet Light Sources

“…Although we admit that we currently do not have a thorough report with two-color fields, we believe that at least the results demonstrated that both odd and even order harmonics are enhanced due to doping. Previous researchers demonstrated HHG from the plasma plumes of various materials and gas jets using TCP of different wavelengths with orthogonal polarization of SH wavelengths. − For TCP measurements, a BBO crystal (type 1, 0.2 mm thickness) is placed 20 cm away from the focusing lens providing a SH conversion efficiency of about 20% at I fs = 4.5 × 10 14 W cm –2 . Therefore, the measured intensity distribution ratio of the fundamental and SH signal was 1.8:1.…”

“…It is known that SCP generates only odd harmonics, whereas both odd and even harmonics could be generated with TCP and that too with a higher conversion efficiency. Such an enhancement can be attributed to the selection of a short quantum path component of a denser electron wave packet and a higher ionization rate. − Overall, Ni-doped CsPbBr 3 NCs possessed intense harmonic spectra for TCP compared to SCP. Particularly, in the case of CsPbBr 3 for ps HP and ns LIP, the harmonic yield was enhanced by 1.75 and 7 times for TCP than SCP.…”

High-Order Harmonics Generation in MoS2 Transition Metal Dichalcogenides: Effect of Nickel and Carbon Nanotube Dopants

“…Hence, to increase the yield and cut-off energy of harmonics, different schemes like resonance-induced enhancement, quasi-phase matching of harmonics, application of multi-particle species, optimization of laser parameters, use of polarization structured beams, multicolor excitation, etc. have been introduced [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ].…”