We report on a picosecond two-stage double-pass chirped pulse amplifier based on a low doping level Yb:YAG rods. After compression, it provides output pulses with a pulsewidth of 1.15 ps and an energy of more than 20 mJ at a repetition rate of 100 Hz with a beam quality of M² ∼1.05. These pulses were frequency doubled in a two-cascaded second harmonic converter based on LBO and BBO crystals with an output energy of 12 mJ and 5 mJ at 515 nm, suitable for simultaneously pumping OPCPA cascades.

We report efficient amplification of chirped supercontinuum pulses in a two-stage stimulated Raman amplifier based on double tungstate [ K G d ( W O 4 ) 2 ] crystals, pumped with 1.2 ps transform-limited pulses at a 1030 nm wavelength. The second stage demonstrates a conversion efficiency of 55% with an output pulse energy of 0.6 mJ at a 1135 nm wavelength. The amplified Stokes bandwidth is 10 times the pump bandwidth, providing 145 fs pulses after compression.

We report a study of a compact, scalable up to TW peak power OPCPA with ∼1.2 ps pump pulses delivered from a Yb:YAG laser. Passive synchronization was ensured by using a small portion of the energy to generate a stable supercontinuum in the YAG, and the rest was directed to pump the three OPCPA stages. The temporal shape of the pump pulse was controlled by the degree of depletion of fundamental radiation in a two-cascade second harmonic converter. Under optimal conditions, the energy of amplified pulses reached ∼2.1 mJ with the support of a spectral bandwidth sufficient for a transform-limited pulse width of 8.6 fs.

We present a compact and cost-effective mJ-level femtosecond laser system operating at a center wavelength of approximately 2.15 μm. An affordable two-stage ytterbium-doped yttrium aluminum garnet (Yb:YAG) chirped pulse amplifier provides more than 10 mJ, approximately 1.2 ps pulses at 1030 nm to pump a three-stage optical parametric chirped pulse amplifier (OPCPA) based on bismuth borate crystals and to drive the supercontinuum seed in the YAG crystal. The energy of the amplified pulses in the wavelength range of 1.95–2.4 μm reached 2.25 mJ with a pump-to-signal conversion efficiency of approximately 25% in the last OPCPA stage. These pulses were compressed to 38 fs in a pair of Suprasil 300 glass prisms.

Three different stimulated Brillouin scattering (SBS) configurations in perfluorooctane were experimentally compared to achieve the ultimate compression of ~1.1 ns pulses from a commercially available Nd:YAG mini-laser. These schemes contained either a focusing lens and a plane feedback mirror, a spherical mirror, or variable pulse splitting to provide self-seeding of the SBS. In the optimal configuration with a focusing lens and return mirror, 93 ps pulses with an energy of 9.5 mJ were achieved at the output of the double-pass phase-conjugated Nd:YAG amplifier. The resulting diffraction-free, high-quality beams with M²~1.2 and excellent pointing stability are of practical interest for scientific, medical, and industrial applications.

The synthesis of adjacent overlapped Stokes spectra in two stages of a transient stimulated Raman chirped-pulse amplifier, tuned respectively to the vibrational modes at 901 and 767 cm⁻¹ of a potassium gadolinium tungstate [KGd(WO₄)₂] crystal, is demonstrated. The contribution of the spatio-temporal overlap of seed and pump pulses, as well as the self-phase modulation, was investigated. The noncollinear configuration allows the composite bandwidth at the central wavelength of 1120 nm to be increased by a factor of 23 compared to the pump pulse bandwidth of 1.6 nm. After reaching a conversion efficiency of 35% in the second stage, the compressibility of a chirped Stokes pulse with a tailored spectrum was also investigated.