Numerical Model of Broadband Pulse Amplification in Cryogenic Yb:YLF Regenerative Amplifiers

High energy and high average power ultrafast lasers, delivering femtosecond pulses with hundreds of millijoule energy, are important for scientific and industrial applications. Such laser systems are based on the chirped pulse amplification technique, in which a stretched pulse from a mode-locked laser oscillator is amplified in several amplifier stages and then compressed. Since the typical energy from an oscillator is in the nanojoule range, a regenerative amplifier (RA) is usually employed as the first amplifier stage, where the seed pulse experiences about 6 orders of magnitude gain, resulting in millijoule level output pulse energies [1]. The development of an amplifier requires a numerical model that allows the simulation of gain dynamics considering: (1) pump and seed saturation effects; (2) crystal parameters; (3) spectral evolution of the seed upon amplification; (4) temperature conditions in the gain element.