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.

A novel tiled Ti:sapphire (Ti:S) amplifier was experimentally demonstrated with >1 J amplified chirped pulse output. Two Ti:S crystals having dimensions of 14 mm× 14 mm× 25 mm were tiled as the gain medium in a four-pass amplifier. Maximum output energy of 1.18 J was obtained with 2.75 J pump energy. The energy conversion efficiency of the tiled Ti:S amplifier was comparable with a single Ti:S amplifier. The laser pulse having the maximum peak power of 28 TW was obtained after the compressor. Moreover, the influence of the beam gap on the far field was discussed. This novel tiled Ti:S amplifier technique can provide a potential way for 100 PW or EW lasers in the future.

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.

In this Letter, we experimentally explore the pulse-contrast degradation caused by surface reflection in optical parameter chirped-pulse amplification. Different pump-to-signal conversion efficiencies and post-pulses with different intensities are obtained by changing the seed-pulse or pump-pulse energy and inserting etalons with different reflection coefficients, respectively. The contrast measurements show that the generated first pre-pulse intensity is proportional to the product of the surface reflection intensity ratio and the square of the pump-to-signal conversion efficiency.

We report on our high-contrast laser based on high-contrast, high-energy seed injection, low-gain optical parametric chirped pulse amplification (OPCPA), and Nd:glass amplifiers, which can be used as the high-contrast front end of a high-power Nd:glass chirped pulse amplification (CPA) laser system. The energy of the stretched 1053 nm high-contrast seed pulse increases to 60 μJ by optimizing the frequency doubling crystal in the pulse cleaning device. After passing through a two-stage low-gain OPCPA, a 2-pass 2-rod Nd:glass amplifier, and a compressor the amplified pulse of 131 mJ/282 fs is achieved. The third-order correlation scanning measurement shows that the pulse contrast in the tens of ps range is about 10 7–10 8. With the high-contrast seed passing through the stretcher and compressor only, the contrast measurement indicates that the stretching-compressing process leads mainly to the contrast degradation of the amplified pulse.

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 beforethe main pulse, respectively.