Effect of THz-bandwidth incoherent laser radiation on bulk damage in potassium dihydrogen phosphate crystals.

The laser-damage performance characteristics of potassium dihydrogen phosphate (KDP) samples under exposure to a distinctive broadband incoherent laser pulse are investigated. A laser system providing such pulses is intended to explore improved energy-coupling efficiency on the target in direct-drive inertial confinement fusion experiments and provides incoherent bandwidths as large as 10 THz in a nanosecond pulse. A consequence of this bandwidth is very rapid fluctuations in intensity capable of reaching maxima much larger than the average intensity within the pulse.

Final amplifier of an ultra-intense all-OPCPA system with 13-J output signal energy and 41% pump-to-signal conversion efficiency.

Optical parametric chirped-pulse amplification (OPCPA) using high-energy Nd:glass lasers has the potential to produce ultra-intense pulses (>10 W/cm). We report on the performance of the final high-efficiency amplifier in an OPCPA system based on large-aperture (63 × 63-mm) partially deuterated potassium dihydrogen phosphate (DKDP) crystals. The seed beam (180-nm bandwidth, 110 mJ) was provided by the preceding OPCPA stages.

Design and optimization of a high-energy optical parametric amplifier for broadband, spectrally incoherent pulses.

Spectrally incoherent laser pulses with sufficiently large fractional bandwidth are in demand for the mitigation of laser-plasma instabilities occurring in high-energy laser-target interactions. Here, we modeled, implemented, and optimized a dual-stage high-energy optical parametric amplifier for broadband, spectrally incoherent pulses in the near-infrared. The amplifier delivers close to 400 mJ of signal energy through noncollinear parametric interaction of 100-nJ-scale broadband, spectrally incoherent seed pulses near 1053 nm with a narrowband high-energy pump operating at 526.

Effect of the pump beam profile and wavefront on the amplified signal wavefront in optical parametric amplifiers.

We present a theoretical and experimental analysis of the signal phase introduced by the pump-beam wavefront and spatial profile during optical parametric amplification (OPA) process. The theory predicts the appearance of an additional wavefront in the amplified signal beam that is proportional to the spatial derivative of the pump-beam wavefront. The effect of the pump-beam profile on the signal-beam wavefront is also investigated.

Spectral and temporal shaping of spectrally incoherent pulses in the infrared and ultraviolet.

Laser-plasma instabilities (LPIs) hinder the interaction of high-energy laser pulses with targets. Simulations show that broadband spectrally incoherent pulses can mitigate these instabilities. Optimizing laser operation and target interaction requires controlling the properties of these optical pulses.

Broadband sum-frequency generation of spectrally incoherent pulses.

We study and demonstrate the nonlinear frequency conversion of broadband optical pulses from 1053 nm to 351 nm using sum-frequency generation with a narrowband pulse at 526.5 nm. The combination of angular dispersion and noncollinearity cancels out the wave-vector mismatch and its frequency derivative, yielding an order-of-magnitude increase in spectral acceptance compared to conventional tripling.