Amplification of broad-band chirped pulses up to the 100-mJ level using alexandrite-pumped neodymium-doped glasses

An alexandrite laser is used to longitudinally end-pump mixed Nd:glass rods in a multipass arrangement in order to amplify chirped pulses in the 50-100-mJ range at a 1-Hz repetition rate. This system has a broad-band capability of up to 8-10 nm output bandwidth. We have developed a model, which in our specific case of amplification of chirped-pulse, takes into account the exact configuration of the rods, their spectral properties, and the longitudinal pumping geometry. An agreement between experiment and theory is obtained by assuming a pump quantum efficiency of the order of 60%.