Attosecond pulse generation at ELI-ALPS 100 kHz repetition rate beamline

Abstract

We generate attosecond pulse train (APT) in argon driven by the high repetition rate (HR) laser of the extreme light infrastructure-attosecond light pulse source (ELI-ALPS), providing 100 kHz, 80 W, 1030 nm, 40 fs pulses from a fiber chirped-pulse amplification (fiber-CPA) laser system. Under the current operating conditions of the high harmonic generation beamline (HR-GHHG), we observed the average pulse duration to be 395 as measured using the technique of reconstruction of attosecond beating by interference of two-photon transitions. The beamline uses an annular-shape laser beam so that the main part of the driving laser co-propagating with the APT can be eliminated by reflection on a holey mirror. An additional 100 nm aluminum foil is used to filter out the remaining laser and the low order harmonics, allowing 2 pJ APT with a bandwidth from 25 eV to 50 eV to be transported to the target position where the APT interacts with matter. The implementation of the HR-GHHG beamline in ELI-ALPS delivering attosecond pulse trains at 100 kHz paves the way for time-resolved experiments in the infrastructure, especially those that involve rare events and coincidence analysis, both of which need high statistics.

High-Flux 100 kHz Attosecond Pulse Source Driven by a High-Average Power Annular Laser Beam

“…However, with the increase of laser power, this portion will become stronger and it must be considered. In the high-repetition rate regime of ~100 kHz, several laboratories have used annular laser beams to generate high-order harmonics [27,70], while the measurement of the attosecond temporal duration was only reported in our previous work at ELI-ALPS [52].…”

“…We make this distinction because temporal characterization is a demonstration of the attosecond pump-probe capability. As shown in Figure 1, single-pass HHG can provide high harmonics [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] up to tens of nJ per shot at 1 MHz by using powerful driving lasers with an average power up to ~100 W [37][38][39][40][41][42][43] and the attosecond pulses [44][45][46][47][48][49][50][51][52][53][54][55] up to hundreds of pJ per shot at 100 kHz. Intracavity HHG can deliver the high harmonics with the repetition rates up to hundreds of MHz [56][57][58][59][60][61][62][63].…”

All-Optical Experimental Control of High-Harmonic Photon Energy

“…The experiments are performed using the HR GHHG GAS beamline of the Extreme Light Infrastructure-Attosecond Light Pulse Source (ELI-ALPS) Research Facility [2,37]. The high-harmonic generation beamline [37] is seeded by one of the user-ready laser sources of ELI-ALPS [38]: the high-repetition-rate (HR-1) laser system is specified to emit 1 mJ, sub-2-cycle pulses at 1030 nm [38]. The heart of the system is a powerful subpicosecond ytterbium fiber-based chirped pulse amplifier (CPA).…”

“…Compared with the beamline configuration detailed by Ye et al in Ref. [37] only a minor modification is made on the beamline (Fig. 1): one of the steering mirrors is replaced by a custom-made SDU [39], while the other optics remain unchanged.…”

“…The residual IR is eliminated by an aluminum filter. After further propagation through XUV optics [37], the HHG beam reaches the XUV spectrometer section, consisting of an XUV grating, a microchannel plate, a phosphor screen, and a CMOS camera.…”