High-Contrast Broadband Seed Generation for Multi-Petawatt OPCPA Lasers

Parametric front-ends are widely used to seed petawatt lasers due to the inherent high contrast and broad bandwidth.We present the design and numerical modeling of a system for seeding petawatt-class lasers based on optical parametric amplification in deuterated potassium dihydrogen phosphate (DKDP) crystals.In the proposed scheme, supercontinuum pulses in the short-wavelength infrared are amplified in mercury gallium sulfide (HGS) crystals, followed by secondharmonic generation.Our simulations predict a relative contrast enhancement up to 10 7 , providing a robust basis for the subsequent amplification stages.To the best of our knowledge, this is the first study of parametric amplification in HGS crystals pumped at 1030 nm in the femtosecond regime, enabling pumping by industrial-class Yb lasers.The high nonlinearity of HGS (>10 times that of the typical BBO or BIBO) allows the use of thin crystals, reducing the accumulated mismatching and hence permitting Fourier limited pulse durations of ∼16 fs.