A new avenue of opportunity in the field of intense, ultrashort laser pulse technology and its applications has opened as a result of the development of the laser materials Cr-doped LiSAF and Cr-doped LiCAF. These materials, like no others yet developed, display the most attractive characteristics of a solid state laser material required for the generation of ultra-intense, ultrashort laser pulses. They have high gain and energy storage properties, good optical properties, a high damage threshold and can be grown in large sizes. Moreover, they uniquely combine long fluorescence lifetimes ( 70 us for LiSAF and 130 us for LiCAF) and the broadest spectral emission bandwith known (220nm for LiSAF), making possible, for the first time, the amplification with high gain, of ultrashort (< 100fs) pulses with flashlamp-pumped, large diameter, solid state laser modules. The implications will be considerable for future applications of ultrashort, high intensity laser technology, in the development of laboratory x-ray lasers, sub-picosecond x-ray studies, and particle acceleration. We will make a comprehensive investigation of all the physical properties of these two materials associated with their use as high gain amplifiers of ultrashort laser pulses. This will include a full examination of the basic spectral and atomic properties of Cr-doped LiSAF and LiCAF pertaining to broadband pulse amplification, their capacity to amplify short pulses, the effectiveness with which chirped pulse amplification (CPA) can extract energy, and those material properties affecting their use in wide aperture, multi-segmented array (MSA) amplifiers. This study will therefore address all the issues necessary to incorporate these new materials as a major laser amplifier medium. Armed with data produced by this study, we will then be able, in future work, to move forward towards the construction of lasers capable of emitting tens, perhaps hundreds of joules in times of less than 100fs, focusable to intensities greater than 1020W/cm2.
