Modification of modulated plasma plumes for the quasi-phase-matching of high-order harmonics in different spectral ranges

Abstract

We demonstrate the technique allowing the fine tuning of the distance between the laser-produced plasma plumes on the surfaces of different materials, as well as the variation of the sizes of these plumes. The modification of plasma formations is based on the tilting of the multi-slit mask placed between the heating laser beam and target surface, as well as the positioning of this mask in the telescope placed on the path of heating radiation. The modulated plasma plumes with the sizes of single plume ranging between 0.1 and 1 mm were produced on the manganese and silver targets. Modification of the geometrical parameters of plasma plumes proved to be useful for the fine tuning of the quasi-phase-matched high-order harmonics generated in such structures during propagation of the ultrashort laser pulses. We show the enhancement of some groups of harmonics along the plateau range and the tuning of maximally enhanced harmonic by variable modulation of the plasma. V C 2015 AIP Publishing LLC. [http://dx.

High-order harmonics enhancement in laser-induced plasma

“…This equation assumes that, by using longer jets, one can tune the enhanced group of harmonics towards the region of enhancement of a single harmonic in the case of indium plasma (H21 for 1310 nm pumps and H13 for 800 nm pumps). Such a tuning, but only up to the 45 nm region was reported in a few publications (for example 78 ). The maximally enhanced harmonics ( q QPM ) followed the rule when the product l × N e was maintained constant at a fixed electron density of the silver plasma.…”

Application of 150 kHz Laser for High-Order Harmonic Generation in Different Plasmas

“…Correspondingly, the application of fiber chirped pulse amplification systems, delivering higher pulse repetition rates (100 kHz and higher) compared with commonly used Ti: sapphire class lasers, may open new opportunities for HHG from LPPs. Different processes, such as the local field enhancement in quantum dots [13], resonance enhancement of single harmonics in metal plasmas [14], the realization of the quasi-phase matching conditions in periodically modulated plasma plumes [15,16], and nonlinear spectroscopy of ablated materials [17], could be more easily analyzed using the high pulse repetition coherent XUV sources. The generation of high harmonics from gas jets allowed achieving μW harmonics between 45 nm and 61 nm (H23-H17), at a repetition rate of 50 kHz [18].…”