Hybrid femtosecond lasers combine the chirped pulse amplification (CPA) in laser media with optical parametric chirped pulse amplification (OPCPA) in nonlinear crystals. Gain bandwidths as broad as 150 nm can be obtained by noncollinear optical parametric chirped pulse amplification in nonlinear crystals. Therefore, stretched laser pulses compressible to sub-10-fs pulse duration can be amplified in crystals like beta-barium borate (BBO) and potassium dideuterium phosphate (DKDP). The ultra-broad phase-matching bandwidth near 800 nm wavelength of beta-barium borate crystals pumped by green nanosecond lasers and the gain bandwidth of Ti:sapphire laser crystals are practically overlapped. Optical parametric chirped pulse amplification in beta-barium borate crystals at low-energy level in the laser system Front-End (FE), combined with high-energy chirped pulse amplification in Ti:sapphire crystals, represents an advanced solution for petawatt-class femtosecond laser systems. A couple of worldwide developed hybrid amplification high-power femtosecond laser systems are presented. The configuration and output beam characteristics of the hybrid amplification petawatt laser of the Extreme Light Infrastructure: Nuclear Physics (ELI-NP) facility are described.
Part of the book: High Power Laser Systems