Relativistic-intensity near-single-cycle light waveforms at kHz repetition rate

Abstract

The development of ultra-intense and ultra-short light sources is currently a subject of intense research driven by the discovery of novel phenomena in the realm of relativistic optics, such as the production of ultrafast energetic particle and radiation beams for applications. It has been a long-standing challenge to unite two hitherto distinct classes of light sources: those achieving relativistic intensity and those with pulse durations approaching a single light cycle. While the former class traditionally involves large-scale amplification chains, the latter class places high demand on the spatiotemporal control of the electromagnetic laser field. Here, we present a light source producing waveformcontrolled 1.5-cycle pulses with a 719 nm central wavelength that can be focused to relativistic intensity at a 1 kHz repetition rate based on nonlinear post-compression in a long hollow-core fiber. The unique capabilities of this source allow us to observe the first experimental indications of light waveform effects in laser wakefield acceleration of relativistic energy electrons.

Demonstration of stable long-term operation of a kilohertz laser-plasma accelerator

“…The laser generates ≈ 10 mJ pulses with central wavelength λ 0 = 800 nm, and full width at half maximum (FWHM) duration of 23 fs. The pulses are then post-compressed in a 2.5 m-long hollow core fiber (HCF) filled with Helium gas 27,28 . Varying the pressure of Helium in the fiber gives control over the spectral bandwidth and therefore over the pulse duration, which was tuned between 3.5 fs and 23 fs in the experiment, see Fig.…”

“…The experiment was conducted using the Salle Noire laser system at LOA [36,37], which provides 10 mJ, 25 fs FWHM laser pulses at kilohertz repetition rate, with a central wavelength λ 0 ¼ 800 nm. The laser pulse is then post-compressed in a helium-filled hollow core fiber (HCF) resulting in a broad spectrum, 4.0 fs pulse.…”

Towards isolated attosecond electron bunches using ultrashort-pulse laser-solid interactions

“…This is to produce electron bunches at higher energy and more separable from the background while keeping a comparable driving laser pulse energy. It has been shown that CEP plays a role in the electron acceleration process in LWFA 28 and in nanoplasma acceleration 29 . Figure 4 demonstrates the generated single bunches using various carrier-envelope phases.…”

High-energy few-cycle pulses: post-compression techniques

“…The HCF technology is the only post-compression technique which reaches the high-energy few-cycle regime with above-mJ, sub-3-cycle pulses (red-shaded area in Figure 9), clearly dominating this field at present. Two of the three best results in this regime were obtained with SF-HCFs (6.1 mJ/ 3.8 fs [153] and 3.5 mJ/3.4 fs [152]) and the third with a long HCF (5 mJ/5 fs [148]). In the terawatt regime the picture is similar: here in addition to the previously mentioned works there is a preliminary result achieved with SF-HCF technology (40 mJ/25 fs [201]).…”

“…In the current setup all focusing/recollimating optics are situated in the vacuum/gas chambers and only a large collimated beam at low intensity passes the windows without inducing unwanted nonlinearities. In this way well-controlled CEP-stable 3.5 fs pulses with 3.5 mJ are routinely generated [152]. Recently, an up-scaled version of the system has been commissioned at the Max Born Institute with an overall length of 8.2 m where 14 mJ 50 fs pulses are compressed to 1.5 optical cycles at 3.8 fs duration with an output energy of 6.1 mJ with a peak power of 1.2 TW [153] clearly breaking the TW barrier.…”