We demonstrate an ultra-broadband high temporal contrast infrared laser source based on cascaded optical parametric amplification, hollow-core fiber (HCF) and second harmonic generation processes. In this setup, the spectrum of an approximately 1.8 μm laser pulse has near 1 μm full bandwidth by employing an argon gas-filled HCF. Subsequently, after frequency doubling with cascaded crystals and dispersion compensation by a fused silica wedge pair, 9.6 fs (~3 cycles) and 150 μJ pulses centered at 910 nm with full bandwidth of over 300 nm can be generated. The energy stability of the output laser pulse is excellent with 0.8% (root mean square) over 20 min, and the temporal contrast is >1012 at –10 ps before the main pulse. The excellent temporal and spatial characteristics and stability make this laser able to be used as a good seed source for ultra-intense and ultrafast laser systems.

We report on a vortex laser chirped-pulse amplification (CPA) system that delivers pulses with a peak power of 45 TW. A focused intensity exceeding 1019 W/cm2 has been demonstrated for the first time by the vortex amplification scheme. Compared with other schemes of strong-field vortex generation with high energy flux but narrowband vortex-converting elements at the end of the laser, an important advantage of our scheme is that we can use a broadband but size-limited q-plate to realize broadband mode-converting in the front end of the CPA system, and achieve high-power amplification with a series of amplifiers. This method is low cost and can be easily implemented in an existing laser system. The results have verified the feasibility to obtain terawatt and even petawatt vortex laser amplification by a CPA system, which has important potential applications in strong-field laser physics, for example, generation of vortex particle beams with orbital angular momentum, fast ignition for inertial confinement fusion and simulation of the extreme astrophysical environment.

In this paper, we report the recent progress on the $1~\text{PW}/0.1~\text{Hz}$ laser beamline of Shanghai Superintense Ultrafast Laser Facility (SULF). The SULF-1 PW laser beamline is based on the double chirped pulse amplification (CPA) scheme, which can generate laser pulses of 50.8 J at 0.1 Hz after the final amplifier; the shot-to-shot energy fluctuation of the amplified pulse is as low as 1.2% (std). After compression, the pulse duration of 29.6 fs is achieved, which can support a maximal peak power of 1 PW. The contrast ratio at $-80~\text{ps}$ before main pulse is measured to be $2.5\times 10^{-11}$. The focused peak intensity is improved by optimizing the angular dispersion in the grating compressor. The maximal focused peak intensity can reach $2.7\times 10^{19}~\text{W}/\text{cm}^{2}$ even with an $f/26.5$ off-axis parabolic mirror. The horizontal and vertical angular pointing fluctuations in 1 h are measured to be 1.89 and $2.45~\unicode[STIX]{x03BC}\text{rad}$, respectively. The moderate repetition rate and the good stability are desirable characteristics for laser–matter interactions. The SULF-1 PW laser beamline is now in the phase of commissioning, and preliminary experiments of particle acceleration and secondary radiation under 300–400 TW/0.1 Hz laser condition have been implemented. The progress on the experiments and the daily stable operation of the laser demonstrate the availability of the SULF-1 PW beamline.

We demonstrate a high-contrast, joule-level Nd:glass laser system operating at 0.5 Hz repetition rate based on a double chirped pulse amplification (CPA) scheme. By injecting high-contrast, high-energy seed pulses into the Nd:glass CPA stage, the pulse energy is amplified to 1.9 J through two optical parametric CPA stages and two Nd:glass amplifiers. The temporal contrast of compressed pulse is measured down to the level of $10^{-8}$ at tens of ps, and $10^{-10}$ near 200 ps before the main pulse, respectively.

We develop a splicing technology of Ti:sapphire crystals for a high-energy chirped pulse amplifier laser system that can suppress the parasitic lasing to improve the amplification efficiency compared to a large-size single Ti:sapphire crystal amplifier. Theoretical investigations on the characteristics of the amplifier with four splicing Ti:sapphire crystals, such as parasitic-lasing suppression and amplification efficiencies, are carried out. Some possible issues resulting from this splicing technology, including spectral modulation, stretching or splitting of the temporal profile, and the sidelobe generation in the spatial domain (near field and far field), are also investigated. Moreover, the feasibility of the splicing technology is preliminarily demonstrated in an experiment with a small splicing Ti:sapphire crystals amplifier. The temporal profile and spatial distribution of the output pulse from the splicing Ti:sapphire crystal amplifier are discussed in relation to the output pulse from a single Ti:sapphire crystal amplifier.