Compact high-flux X-ray source based on irradiation of solid targets by gigahertz and megahertz bursts of femtosecond laser pulses

Abstract

In this study, we demonstrate the significant increase in the hard X-ray yield (more than 1011 photons/s in 4π solid angle in 6 - 40 keV range) that can be achieved in an ambient air environment when solid targets are irradiated by sequences of high average power (90 W) bursts of femtosecond laser pulses, generated in GHz burst laser amplifier operated at high repetition rate (100 kHz). The combination of the prepulse and ∼ 10 times greater driving pulse not only enhances X-ray generation efficiency (∼ 10−6) by more than two orders of magnitude compared to the single pulse regime but also protects a target allowing continuous operation for 3 hours with only 30% predictable and gradual drop of X-ray yield. In addition, we show that X-ray yield enhancement becomes around 6 times more pronounced at higher repetition rates (100 kHz compared to < 5 kHz). The simplicity and relative cost-effectiveness of the presented X-ray source makes it an attractive solution for future applications in ultrafast X-ray imaging and spectroscopy.

Solid-state femtosecond UV lasers: recent advances and challenges

“…Our experiments show that, by introducing a prepulse before the main pulse, the X-ray yield and conversion efficiency (from IR to X-rays) might increase more than 200 times compared with the single pulse regime (see Figure 19. a) [43]. In Figure 19.…”

“…Also, LLP sources are able to produce a high degree of spatial coherence as a result of their small spot size. Such source features find applications in areas like physics, chemistry, biology, medicine, and even the semiconductor industry, where the dimensions of lithographic features are approaching the X-ray wavelengths [43].…”

Supercontinuum generation in bulk solid-state material with bursts of femtosecond laser pulses

“…Burst trains of femtosecond laser pulses emerge as a powerful tool for laser material processing, offering a variety of technological innovations in micromachining of metals 1 – 5 , glasses 6 – 12 , semiconductors 13 – 15 , polymers 16 and biomaterials 17 . Burst-mode two-photon polymerization was considered to deliver microstructures with smaller feature size 18 , while irradiation of solid targets with femtosecond pulse bursts was demonstrated to significantly increase of the hard X-ray yield 19 . For what concerns laser wavelength conversion processes, generation second and fourth harmonics with femtosecond pulse bursts was demonstrated 20 .…”